Cyclic AMIDES formed from aminocarboxylic acids by the elimination of water. Lactims are the enol forms of lactams.
Changing an open-chain hydrocarbon to a closed ring. (McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
A 13-amino acid peptide derived from proteolytic cleavage of ADRENOCORTICOTROPIC HORMONE, the N-terminal segment of ACTH. ACTH (1-13) is amidated at the C-terminal to form ACTH (1-13)NH2 which in turn is acetylated to form alpha-MSH in the secretory granules. Alpha-MSH stimulates the synthesis and distribution of MELANIN in MELANOCYTES in mammals and MELANOPHORES in lower vertebrates.
A class of organic compounds containing a ring structure made up of more than one kind of atom, usually carbon plus another atom. The ring structure can be aromatic or nonaromatic.
Four-membered cyclic AMIDES, best known for the PENICILLINS based on a bicyclo-thiazolidine, as well as the CEPHALOSPORINS based on a bicyclo-thiazine, and including monocyclic MONOBACTAMS. The BETA-LACTAMASES hydrolyze the beta lactam ring, accounting for BETA-LACTAM RESISTANCE of infective bacteria.
Compounds consisting of glucosamine and lactate joined by an ether linkage. They occur naturally as N-acetyl derivatives in peptidoglycan, the characteristic polysaccharide composing bacterial cell walls. (From Dorland, 28th ed)
The phenomenon whereby compounds whose molecules have the same number and kind of atoms and the same atomic arrangement, but differ in their spatial relationships. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 5th ed)
Brief reversible episodes of focal, nonconvulsive ischemic dysfunction of the brain having a duration of less than 24 hours, and usually less than one hour, caused by transient thrombotic or embolic blood vessel occlusion or stenosis. Events may be classified by arterial distribution, temporal pattern, or etiology (e.g., embolic vs. thrombotic). (From Adams et al., Principles of Neurology, 6th ed, pp814-6)
A cyclohexylamido analog of PENICILLANIC ACID.
The location of the atoms, groups or ions relative to one another in a molecule, as well as the number, type and location of covalent bonds.
The creation of an amine. It can be produced by the addition of an amino group to an organic compound or reduction of a nitro group.
A plant genus of the family CAPPARACEAE that contains cleogynol and 15alpha-acetoxycleomblynol (dammaranes) and 1-epibrachyacarpone (a triterpene), and ISOTHIOCYANATES.
A family of G-protein-coupled receptors that have specificity for MELANOCYTE-STIMULATING HORMONES and ADRENOCORTICOTROPIC HORMONE. There are several subtypes of melanocortin receptors, each having a distinct ligand specificity profile and tissue localization.
A group of antibiotic aminoglycosides differing only in the number of repeating residues in the peptide side chain. They are produced by Streptomyces and Actinomyces and may have broad spectrum antimicrobial and some antiviral properties.
Substances that reduce the growth or reproduction of BACTERIA.
A frequent complication of drug therapy for microbial infection. It may result from opportunistic colonization following immunosuppression by the primary pathogen and can be influenced by the time interval between infections, microbial physiology, or host resistance. Experimental challenge and in vitro models are sometimes used in virulence and infectivity studies.
A product of COMPLEMENT ACTIVATION cascade, regardless of the pathways, that forms transmembrane channels causing disruption of the target CELL MEMBRANE and cell lysis. It is formed by the sequential assembly of terminal complement components (COMPLEMENT C5B; COMPLEMENT C6; COMPLEMENT C7; COMPLEMENT C8; and COMPLEMENT C9) into the target membrane. The resultant C5b-8-poly-C9 is the "membrane attack complex" or MAC.
Unsaturated hydrocarbons of the type Cn-H2n, indicated by the suffix -ene. (Grant & Hackh's Chemical Dictionary, 5th ed, p408)
Organic compounds containing the carboxy group (-COOH). This group of compounds includes amino acids and fatty acids. Carboxylic acids can be saturated, unsaturated, or aromatic.
A genus of bacteria that form a nonfragmented aerial mycelium. Many species have been identified with some being pathogenic. This genus is responsible for producing a majority of the ANTI-BACTERIAL AGENTS of practical value.
Spectroscopic method of measuring the magnetic moment of elementary particles such as atomic nuclei, protons or electrons. It is employed in clinical applications such as NMR Tomography (MAGNETIC RESONANCE IMAGING).
Organic compounds containing the -CO-NH2 radical. Amides are derived from acids by replacement of -OH by -NH2 or from ammonia by the replacement of H by an acyl group. (From Grant & Hackh's Chemical Dictionary, 5th ed)
The molecular designing of drugs for specific purposes (such as DNA-binding, enzyme inhibition, anti-cancer efficacy, etc.) based on knowledge of molecular properties such as activity of functional groups, molecular geometry, and electronic structure, and also on information cataloged on analogous molecules. Drug design is generally computer-assisted molecular modeling and does not include pharmacokinetics, dosage analysis, or drug administration analysis.
The relationship between the chemical structure of a compound and its biological or pharmacological activity. Compounds are often classed together because they have structural characteristics in common including shape, size, stereochemical arrangement, and distribution of functional groups.
Glycosylated compounds in which there is an amino substituent on the glycoside. Some of them are clinically important ANTIBIOTICS.
An analytical technique for resolution of a chemical mixture into its component compounds. Compounds are separated on an adsorbent paper (stationary phase) by their varied degree of solubility/mobility in the eluting solvent (mobile phase).
Peptides whose amino and carboxy ends are linked together with a peptide bond forming a circular chain. Some of them are ANTI-INFECTIVE AGENTS. Some of them are biosynthesized non-ribosomally (PEPTIDE BIOSYNTHESIS, NON-RIBOSOMAL).
Terrorism on September 11, 2001 against targets in New York, the Pentagon in Virginia, and an aborted attack that ended in Pennsylvania.
A class of saturated compounds consisting of two rings only, having two or more atoms in common, containing at least one hetero atom, and that take the name of an open chain hydrocarbon containing the same total number of atoms. (From Riguady et al., Nomenclature of Organic Chemistry, 1979, p31)
Unstable isotopes of indium that decay or disintegrate emitting radiation. In atoms with atomic weights 106-112, 113m, 114, and 116-124 are radioactive indium isotopes.
A family of cellular proteins that mediate the correct assembly or disassembly of polypeptides and their associated ligands. Although they take part in the assembly process, molecular chaperones are not components of the final structures.
A class of MOLECULAR CHAPERONES found in both prokaryotes and in several compartments of eukaryotic cells. These proteins can interact with polypeptides during a variety of assembly processes in such a way as to prevent the formation of nonfunctional structures.
A class of MOLECULAR CHAPERONES whose members act in the mechanism of SIGNAL TRANSDUCTION by STEROID RECEPTORS.
Proteins which are synthesized in eukaryotic organisms and bacteria in response to hyperthermia and other environmental stresses. They increase thermal tolerance and perform functions essential to cell survival under these conditions.
A family of heat-shock proteins that contain a 70 amino-acid consensus sequence known as the J domain. The J domain of HSP40 heat shock proteins interacts with HSP70 HEAT-SHOCK PROTEINS. HSP40 heat-shock proteins play a role in regulating the ADENOSINE TRIPHOSPHATASES activity of HSP70 heat-shock proteins.
LACTAMS forming compounds with a ring size of approximately 1-3 dozen atoms.
Processes involved in the formation of TERTIARY PROTEIN STRUCTURE.
A plant genus of the family APOCYNACEAE. It contains ellipticine.
Works containing information articles on subjects in every field of knowledge, usually arranged in alphabetical order, or a similar work limited to a special field or subject. (From The ALA Glossary of Library and Information Science, 1983)
A plant genus of the family LYCOPODIACEAE. Members contain ALKALOIDS. Lycopodium oil is obtained from L. clavatum.
A sterol usually substituted with radioactive iodine. It is an adrenal cortex scanning agent with demonstrated high adrenal concentration and superior adrenal imaging.
A group of beta-lactam antibiotics in which the sulfur atom in the thiazolidine ring of the penicillin molecule is replaced by a carbon atom. THIENAMYCINS are a subgroup of carbapenems which have a sulfur atom as the first constituent of the side chain.
Enzymes found in many bacteria which catalyze the hydrolysis of the amide bond in the beta-lactam ring. Well known antibiotics destroyed by these enzymes are penicillins and cephalosporins.
Any tests that demonstrate the relative efficacy of different chemotherapeutic agents against specific microorganisms (i.e., bacteria, fungi, viruses).
A species of gram-negative, aerobic bacteria, commonly found in the clinical laboratory, and frequently resistant to common antibiotics.
Nonsusceptibility of bacteria to the action of the beta-lactam antibiotics. Mechanisms responsible for beta-lactam resistance may be degradation of antibiotics by BETA-LACTAMASES, failure of antibiotics to penetrate, or low-affinity binding of antibiotics to targets.
A mitosporic fungal genus with many reported ascomycetous teleomorphs. Cephalosporin antibiotics are derived from this genus.
A mitosporic fungal species used in the production of penicillin.
The class of all enzymes catalyzing oxidoreduction reactions. The substrate that is oxidized is regarded as a hydrogen donor. The systematic name is based on donor:acceptor oxidoreductase. The recommended name will be dehydrogenase, wherever this is possible; as an alternative, reductase can be used. Oxidase is only used in cases where O2 is the acceptor. (Enzyme Nomenclature, 1992, p9)
A group of antibiotics that contain 6-aminopenicillanic acid with a side chain attached to the 6-amino group. The penicillin nucleus is the chief structural requirement for biological activity. The side-chain structure determines many of the antibacterial and pharmacological characteristics. (Goodman and Gilman's The Pharmacological Basis of Therapeutics, 8th ed, p1065)
A PYRIDOXAL PHOSPHATE containing enzyme that catalyzes the transfer of amino group of L-LYSINE onto 2-oxoglutarate to generate 2-aminoadipate 6-semialdehyde and L-GLUTAMATE.
A species of imperfect fungi from which the antibiotic nidulin is obtained. Its teleomorph is Emericella nidulans.
Attack by water and proton loss converts 5 to 7, which is a tautomer of the final amide. The scope of this reaction has been ... These are annulation reactions and have some utility in the synthesis of natural products; such as lactams and alkaloids. ... The protonated isocyanate is attacked by water forming carbamate 4, which after deprotonation loses carbon dioxide to the amine ... "Cation-π Control of Regiochemistry of Intramolecular Schmidt Reactions en Route to Bridged Bicyclic Lactams" (Communication). J ...
β-lactam antibiotics injure mitochondria by an attack on the metabolic substrate carriers of the inner membrane. Respiratory ... It could also be possible that a reactive intermediate is formed due to the unstable β-lactam ring. The pyridinium side-group ... Conformations around the β-lactam rings are quite similar to the molecular nucleus of penicillin, while those at the carboxyl ... Tune BM (December 1997). "Nephrotoxicity of beta-lactam antibiotics: mechanisms and strategies for prevention". Pediatric ...
The intramolecular attack of these linear acyl derivatives gives rise to cyclic compounds such as lactones or lactams. Addition ... The second step can proceed with either the nucleophilic attack of the halide ion on the α-carbon of the alkyl group or ... There is an nucleophilic attack of Me3NO on the carbon of the carbonyl group which pushes electrons on the metal. The reaction ... Nucleophilic abstraction is a type of an organometallic reaction which can be defined as a nucleophilic attack on a ligand ...
... despite sharing the β-lactam ring that is characteristic of β-lactam antibiotics. However, the similarity in chemical structure ... This restructures the clavulanic acid molecule, creating a much more reactive species that attacks another amino acid in the ... β-lactam synthetase is a 54.5 kDa protein that is encoded by orf3 of the clavulanic acid gene cluster, and shows similarity to ... The β-lactam like structure of clavulanic acid looks structurally similar to penicillin, but the biosynthesis of this molecule ...
Due to the mechanism of their attack on bacterial cell wall synthesis, β-lactams are considered to be bactericidal. Unlike β- ... which would otherwise be resistant to β-lactam antibiotics), as outlined below. Cefotaxime, like other β-lactam antibiotics, ... As a β-lactam antibiotic in the third-generation class of cephalosporins, cefotaxime is active against numerous Gram-positive ... Kasten B, Reski R (1997). "β-Lactam antibiotics inhibit chloroplast division in a moss (Physcomitrella patens) but not in ...
The hydroperoxy ligand deprotonates the amide which then closes the β-lactam ring by a nucleophilic attack at the thioaldehyde ... A second hydrogen transfer occurs, most likely producing an isopropyl radical which closes the thiazolidine ring by attacking ... which are different types of β-lactam antibiotics. This class of antibiotics is the most widely used. They act by inhibiting ...
They are bicyclic ring systems containing a β-lactam moiety fused with a five-member thiazolidine ring. Due to ring strain and ... Under acidic conditions, the water acts as a nucleophile that attacks the electrophilic carbon of the carbonyl group. Under ... Based on the similar strain energies observed in penams and standalone β-lactam rings, the fused five-member ring likely does ... Also, cleavage of the C-N bond is thermodynamically favorable, since opening of the β-lactam ring reduces ring strain. Ring- ...
These electron-donating groups make the olefin nucleophilic enough to attack electrophilic initiators or growing polymer chains ... Heterocyclic monomers that are cationically polymerized are lactones, lactams and cyclic amines. Upon addition of an initiator ...
... cleaving the beta-lactam ring in the process. In a second step, nucleophilic attack by a water molecule cleaves the covalent ... Avibactam on the other hand does not contain a beta-lactam ring (non beta-lactam beta-lactamase inhibitor), and instead binds ... This allows the degraded beta-lactam to diffuse away and frees up the enzyme to process additional beta-lactam molecules. ... Instead they are co-formulated with a β-lactam antibiotic with a similar serum half-life. This is done not only for dosing ...
The R group can be a range of both basic and acidic sensitive functional groups such as esters, THP ethers, and β-lactams. In ... Following the radical attacks the o-isocyano carbon creating the alpha-stannoimidoyl radical. Through radical cyclization a ... a new tin radical is produced and the original attacking radical leaves with the sulfur substituent. This part of the step-wise ...
Generally, (E)-imines form cis β-lactams while (Z)-imines form trans β-lactams. Other substituents affect the stereochemistry ... The first step is a nucleophilic attack by the imine nitrogen on the carbonyl carbon to generate a zwitterionic intermediate. ... 2 cycloaddition to produce a β-lactam 3. The reaction carries particular importance in the synthesis of β-Lactam antibiotics. ... The β-lactam moiety of the first synthetic penicillin was constructed using this cycloaddition, and it remains a valuable tool ...
The reaction proceeds via nucleophilic attack of the α-amino group on the side-chain amide to form a γ-lactam with the ... In the deamidation of an asparagine residue under physiological conditions, the side chain is attacked by the nitrogen atom of ... flexible residue such as glycine whose low steric hindrance leaves the peptide group open for attack. Deamidation reactions ...
The structure of ceftriaxone mimics the D-alanyl-D-alanine moiety, and the PBP attacks the beta-lactam ring in ceftriaxone as ... January 2005). "Beta-lactam antibiotics offer neuroprotection by increasing glutamate transporter expression". Nature. 433 ( ... It is within the β-lactam family of antibiotics. Ceftriaxone selectively and irreversibly inhibits bacterial cell wall ... Hedlund E (September 2011). "The protective effects of β-lactam antibiotics in motor neuron disorders". Experimental Neurology ...
Nitanai Y, Satow Y, Adachi H, Tsujimoto M (Aug 2002). "Crystal structure of human renal dipeptidase involved in beta-lactam ... after which the bridging solvent attacks the face of the carbonyl carbon of the scissile peptide bond. Although DPEP1 shows ... "Crystal Structure of Human Renal Dipeptidase Involved in β-Lactam Hydrolysis." Journal of Molecular Biology 321.2 (2002): 177- ... "Crystal Structure of Human Renal Dipeptidase Involved in β-Lactam Hydrolysis." Journal of Molecular Biology 321.2 (2002): 177- ...
It often exhibits a resistance to β-lactam antibiotics including penicillin and other last resort antibiotics. There has also ... Common mechanisms for resistance include the production of enzymes that attack the structure of antibiotics (for example, β- ... lactamases inactivating β-lactam antibiotics), modification of the target site that the antibiotic targets so that it can no ... aureus in the fact that they have developed resistance to β-lactam antibiotics. Some also express an exotoxin that has been ...
... attacking a variety of enzymes in cells, DNA, RNA by going through cell membrane; Strong selectivity by its thickness of the ... ferrocenyl derivative has wide applications to biological and medical fields such as ferrocene-modified beta-lactam because of ...
1,2-Benzisoxazole is efficiently produced by nucleophilic attack of hydroxylamine-O-sulfonic acid to the carbonyl group of 2- ... for the conversion of aldehydes into nitriles and alicyclic ketones into lactams (cyclic amides), and for the synthesis of ... alicyclic ketones react to provide lactams in high yields. Under basic conditions in the presence of primary amines, ...
Lactams form from cyclisation of amino acids. Lactams form from intramolecular attack of linear acyl derivatives from the ... β-Lactam (4-atom rings) γ-Lactam (5-atom rings) δ-Lactam (6-atom rings) ε-Lactam (7-atom rings) This ring-size nomenclature ... Lactams can polymerize to polyamides. Lactone, a cyclic ester. β-Lactam β-Lactam antibiotics, which includes penicillins 2- ... Lactams form by the acid-catalyzed rearrangement of oximes in the Beckmann rearrangement. Lactams form from cyclic ketones and ...
Attack of the anion at the secondary or tertiary carbon of the aziridinium ring will lead to different products. Extensive ... Condensation of 2-chloronicotinic acid (2) with o-phenylenediamine (1) leads directly to the tricyclic lactam (3) Although the ... investigation of this problem (e.g. Promethazine, ethopropazine, etc.) has established that the product from attack at ...
Beta-lactam antibiotics such as penicillin inhibit the formation of peptidoglycan cross-links in the bacterial cell wall. The ... The cell wall of some gram-positive bacteria can be completely dissolved by lysozymes which attacks the bonds between N- ...
... an enzyme that attacks the β-lactam ring. To overcome this resistance, β-lactam antibiotics can be given with β-lactamase ... β-lactams are classified according to their core ring structures. β-lactams fused to saturated five-membered rings: β-lactams ... β-lactams fused to unsaturated five-membered rings: β-lactams containing 2,3-dihydrothiazole rings are named penems. β-lactams ... β-lactam antibiotics (beta-lactam antibiotics) are antibiotics that contain a beta-lactam ring in their molecular structure. ...
... can act as a nucleophile that attacks the most electrophilic carbon of the ketene to promote the formation of β-lactams. Chiral ... Unlike the Staudinger β-lactam synthesis, the umpolung ketene in the Lectka β-lactam synthesis behaves as the nucleophile ... Achiral ketenes and imines, in the presence of a chiral nucleophilic catalyst, are allowed to react to make β-lactams in high ... Subsequent ring closure leads to the formation of the β-lactam and the regeneration of the chiral nucleophilic organocatalyst. ...
Nucleophiles tend to attack at the aziridine nitrogen when the nitrogen substituent is small (R1= H), and at the oxygen atom ... spirocylic oxaziridines undergo ring expansions to the corresponding lactam. The migrating substituent is determined by a ... sulfimides may be formed from thioethers and α-aminoketones may be formed by attack of corresponding enolates. The transfer of ...
In the next step the electrophilic carbon atom in the nitrilium ion is attacked by water and a proton is donated back to acetic ... Sulfuric acid is the most commonly used acid for commercial lactam production due to its formation of an ammonium sulfate by- ... For example, cyclododecanone can be converted to the corresponding lactam, the monomer used in the production of Nylon 12. The ... Presumably after the phenyl group migrates and expels the cyanate, it then attacks the nitrillium ion formed. In carbon ...
The most commonly studied reactions in this field are the 4π Staudinger β-lactam synthesis and the 4π Nazarov reaction; ... After a second epoxidation of the ring, the nearby nucleophilic nitrogen attacks the electrophilic carbon, forming a five ...
For beta-lactam resistance, the mechanism is by altering penicillin binding protein production which is encoded by mecA. ... of bacteria that attack the cutaneous defense barrier in mammals". Journal of Dermatological Science. 49 (1): 21-31. doi: ... Park J, Friendship RM, Weese JS, Poljak Z, Dewey CE (October 2013). "An investigation of resistance to β-lactam antimicrobials ...
... can undergo attack from a host of nucleophiles, including alcohols, amines, and enolates with fairly slow rates ... Imines such as benzalaniline form β-lactams with diphenyl ketene. With carbonyl compounds β-lactones are formed analogously. ... At present the mechanism of attack is unknown, but work is underway to determine the exact mechanism. The high reactivity of ...
Carbon can then be attacked by nucleophiles (e.g. negatively charged ions, like the cyanide ion) or a negatively charged part ... lactams, hydroxamates, and isocyanates. Examples of inorganic carbonyl compounds are carbon dioxide and carbonyl sulfide.[ ...
... can be inactivated by other beta-lactams, though not to the extent as other aminoglycosides, and is still often used ... Amikacin evades attacks by all antibiotic-inactivating enzymes that are responsible for antibiotic resistance in bacteria, ... Amikacin ends up with only one site where these enzymes can attack, while gentamicin and tobramycin have six. Bacteria that are ... Another group of beta-lactams, the cephalosporins, can increase the nephrotoxicity of aminoglycoside as well as randomly ...
High doses have been observed to cause intense, prolonged panic attacks in stimulant-intolerant users, and there are anecdotal ... both the aromatic ring and side chain takes place followed by an oxidation of the pyrrolidine ring to the corresponding lactam ...
In halolactonization, an alkene is attacked by a halogen via electrophilic addition with the cationic intermediate captured ... be found in Rhynchosia volubilis seeds Valoneic acid dilactone can be isolated from the heartwood of Shorea laeviforia Lactam, ...
are naturally resistant to penicillin and the majority of related beta-lactam antibiotics, but a number are sensitive to ... Theories include: the bacteria might induce systemic resistance in the host plant, so it can better resist attack by a true ...
For example, cyclododecanone can be converted to the corresponding lactam, the monomer used in the production of Nylon 12.[7][8 ... In the next step the electrophilic carbon atom in the nitrilium ion is attacked by water and a proton is donated back to acetic ... Sulfuric acid is the most commonly used acid for commercial lactam production due to its formation of an ammonium sulfate by- ... Presumably after the phenyl group migrates and expels the cyanate, it then attacks the nitrillium ion formed. In carbon ...
Penicillin and related beta lactams work by inhibiting DD-transpeptidase enzyme that is required by bacteria to cross link ... Asperlicin is a novel antagonist of cholecystokinin, a neurotransmitter thought to be involved in panic attacks, and could ...
... attacks the carbonyl to form a covalently linked acyl-enzyme intermediate. This intermediate is then attacked by the second ... Two different bonds in beta-lactams can be cleaved (1 by penicillin acylase and 2 by beta-lactamase). ... For example, attack by an acyl group results in an acyltransferase reaction. Several families of transferase enzymes have ... The lone pair of electrons present on the oxygen or sulfur attacks the electropositive carbonyl carbon.[3] The 20 naturally ...
... prolonged panic attacks in stimulant-intolerant users,[11] and there are anecdotal reports of psychosis from sleep withdrawal ... followed by an oxidation of the pyrrolidine ring to the corresponding lactam, with subsequent detachment and ring opening to ...
Falagas, Matthew E.; Matthaiou, Dimitrios K.; Vardakas, Konstantinos Z. (2006). "Fluoroquinolones vs β-Lactams for Empirical ... in the aftermath of the anthrax attacks in 2001. The action alleged Bayer failed to warn class members of the potential side ... and Beta-Lactams". Pharmaceutics. 3 (4): 865-913. doi:10.3390/pharmaceutics3040865. PMC 3857062 . PMID 24309312.. ... "Fluoroquinolones compared with β-lactam antibiotics for the treatment of acute bacterial sinusitis: a meta-analysis of ...
Electrophiles attack the carbonyl oxygen. This step often precedes hydrolysis, which is catalyzed by both Brønsted acids and ... Cyclic amides are called lactams; they are necessarily secondary or tertiary amides. Functional groups consisting of -P(O)NR2 ...
In halolactonization, an alkene is attacked by a halogen via electrophilic addition with the cationic intermediate captured ... Lactam, a cyclic amide. *Lactim, a cyclic imide. *Lactide, a cyclic diester ...
Most β-lactam antibiotics, including the penicillins, cephalosporins and monolactams contain sulfur.[34] ... These materials tend to be dark-colored semiconductors that are not readily attacked by water or even many acids. They are ...
The most common are β-lactam antibiotics (such as penicillin) followed by aspirin and NSAIDs.[13][25] Other antibiotics are ... During an attack, blood tests for tryptase or histamine (released from mast cells) might be useful in diagnosing anaphylaxis ... It can sometimes be difficult to distinguish anaphylaxis from asthma, syncope, and panic attacks.[3] Asthma however typically ... of people get more than one attack.[46] Exercise-induced anaphylaxis affects about 1 in 2000 young people.[24] ...
One possibly serious, but rare, side effect with vardenafil is heart attack. Also, in rare cases, vardenafil use may cause ...
CS1 maint: Multiple names: authors list (link) Lowe, G. Ridley, D. D. (1973). "Synthesis of ?-lactams by photolytic Wolff ... The Wolff rearrangement yields a ketene as an intermediate product, which can undergo nucleophilic attack with weakly acidic ...
Stilbenes are produced in Eucalyptus sideroxylon in case of pathogens attacks. Such compounds can be implied in the ... "Lead identification of conformationally restricted β-lactam type combretastatin analogues: Synthesis, antiproliferative ... Organisms sometimes synthesize phenolic compounds in response to ecological pressures such as pathogen and insect attack, UV ... are found in plant resin where they may attract benefactors such as parasitoids or predators of the herbivores that attack the ...
The antibodies which the person's immune system developed to attack the Group A Streptococci are in these cases also able to ... beta-lactam antibiotics), a first generation cephalosporin is used.[27] Cephalosporin antibiotics however can still cause ... but retaining drug-sensitivity to beta-lactam antibiotics such as penicillin, emerged in Hong Kong in 2011, accounting for at ... attack the person's own tissues. The following complications result depending on which tissues in the person's body are ...
In case of 64 and 66, the five-membered nitrogen ring is formed by attack on the unactivated C-18 methyl group of the precursor ... reported that the amidyl radical intermediates, produced by photolysis of medium-sized lactams, e.g. 82 in the presence of PhI( ... This observation provided substantial evidence that the radical attack exhibits strong preference for the 2° over 1° hydrogen. ... "Hypervalent organoiodine reagents in the transannular functionalisation of medium-sized lactams: synthesis of 1-azabicyclo ...
Tail addition of the Ojima lactam 51 was not disclosed in detail but finally taxol 52 was formed in several steps similar to ... which blocked the Grignard from attack on carbonate group, to alcohol 32. The newly formed alcohol was protected as the BOM ...
Amino acids and lactamsEdit. *ε-Caprolactam: Crude oil → benzene → cyclohexane → cyclohexanone → cyclohexanone oxime → ... The molecular weight of nylon products so attacked drops, and cracks form quickly at the affected zones. Lower members of the ... Most nylons are made from the reaction of a dicarboxylic acid with a diamine (e.g. PA66) or a lactam or amino acid with itself ... The synthetic route using lactams (cyclic amides) was developed by Paul Schlack at IG Farben, leading to nylon 6, or ...
On 11 March 1955, Fleming died at his home in London of a heart attack. His ashes are buried in St Paul's Cathedral.[2] ... the β-lactam ring, not then known in natural products. This structure was not immediately published due to the restrictions of ...
Antibiotics are classified generally as beta-lactams, macrolides, quinolones, tetracyclines or aminoglycosides. Their ... making it more difficult to find a target for an antifungal drug to attack that does not also exist in the host organism. ...
... the antibodies which the person's immune system developed to attack the group A streptococci are also able to attack the ... If the person is allergic to the family of antibiotics which both penicillin and amoxicillin are a part of (beta-lactam ... This method is only indicated for people who have had complications like recurrent attacks of acute rheumatic fever or ... but retaining drug-sensitivity to beta-lactam antibiotics such as penicillin, emerged in Hong Kong in 2011, accounting for at ...
The mechanism begins with the nucleophilic attack of the 3-position of the "N"-substituted indole to electrophilic aldehyde, ... Hydroxypyrrolidines and Hydroxy-γ- and δ-lactams have been shown to react very diastereoselectively, with good to excellent ...
Lactams, Macrocyclic * Neoplasms / drug therapy* * Neoplasms / metabolism * Rifabutin / analogs & derivatives* * Rifabutin / ... Combinatorial attack on multistep oncogenesis by inhibiting the Hsp90 molecular chaperone Cancer Lett. 2004 Apr 8;206(2):149-57 ...
... can act as a nucleophile that attacks the most electrophilic carbon of the ketene to promote the formation of β-lactams. Chiral ... Unlike the Staudinger β-lactam synthesis, the umpolung ketene in the Lectka β-lactam synthesis behaves as the nucleophile ... Achiral ketenes and imines, in the presence of a chiral nucleophilic catalyst, are allowed to react to make β-lactams in high ... Subsequent ring closure leads to the formation of the β-lactam and the regeneration of the chiral nucleophilic organocatalyst. ...
Lactams form from cyclisation of amino acids. Lactams form from intramolecular attack of linear acyl derivatives from the ... β-Lactam (4-atom rings) γ-Lactam (5-atom rings) δ-Lactam (6-atom rings) ε-Lactam (7-atom rings) This ring-size nomenclature ... Lactams can polymerize to polyamides. Lactone, a cyclic ester. β-Lactam β-Lactam antibiotics, which includes penicillins 2- ... Lactams form by the acid-catalyzed rearrangement of oximes in the Beckmann rearrangement. Lactams form from cyclic ketones and ...
Lactam ring is normally broken down by stomach acid so most penicillins must be administered parenterally ... Beta-lactams contain a 4 membered ring called the what? What does it mimic? ... lactam ring the terminal D-ala-D-ala of peptidoglycan side chains. ... What anti-biotic attacks cytoplasmic synthesis of cell wall subunits? Fosfomycin. Cycloserine ...
Attack by water and proton loss converts 5 to 7, which is a tautomer of the final amide. The scope of this reaction has been ... These are annulation reactions and have some utility in the synthesis of natural products; such as lactams and alkaloids. ... The protonated isocyanate is attacked by water forming carbamate 4, which after deprotonation loses carbon dioxide to the amine ... "Cation-π Control of Regiochemistry of Intramolecular Schmidt Reactions en Route to Bridged Bicyclic Lactams" (Communication). J ...
... lactams in one pot. One of the lactams, with the tri(p-tol)phosphine and 4-cyanophenyl moiety, exhibits fluorescence emission ... The proposed trienoate intermediates, 1,5-dipolar species formed via nucleophilic ?-attack of phosphines toward diynedioates ... We demonstrate a straightforward synthesis of ?-lactams possessing an ?-phosphorus ylide moiety from assembly of phosphines, N- ... One-pot formation of fluorescent ?-lactams having an ?-phosphorus ylide moiety through three-component ?(?)-Michael reactions ...
This form of attack is similar to how a group of antibiotics, called beta-lactams, work. These antibiotics include penicillin, ... Dr Thomas Wood, now at Harvard Medical School, said: "The impact of VgrG2b on target cells mimics the action of beta-lactam ... IMAGE: These are bacteria devastated by attack with the toxic arrowhead. view more ...
The next time you take the drug, these specific antibodies flag it and direct immune system attacks on the substance. Chemicals ... Penicillins belong to a class of antibacterial drugs called beta-lactam antibiotics. Although the mechanisms of the drugs vary ... generally they fight infections by attacking the walls of bacterial cells. In addition to penicillins, other beta-lactams more ...
CbpD-B6 Attacks the Septal Area of the Pneumococcal Cell Wall.. It has previously proved very difficult to express and purify ... Βeta-lactam-resistant pneumococci have acquired so-called low-affinity PBPs, modified PBPs that have much lower affinity for β- ... Since CbpD-B6 attacks the septal region of the cell, we speculated that the enzyme targets the peptidoglycan formed by PBP2x ... The enzyme was allowed to attack the cells for 1 min at 37 °C before they were fixed in a mixture of 2% (v v−1) formaldehyde ...
... lactams in one pot. One of the lactams, with the tri(p-tol)phosphine and 4-cyanophenyl moiety, exhibits fluorescence emission ... attack of phosphines to an enyne in up to 79% yield. The investigated multicomponent reaction tolerates a variety of ... We demonstrate a straightforward synthesis of ?-lactams possessing an ?-phosphorus ylide moiety from assembly of phosphines, N- ... One-pot formation of fluorescent ?-lactams having an ?-phosphorus ylide moiety through three-component ?(?)-Michael reactions ...
In a bioterrorist attack, pulmonary illness may result from the organisms that cause anthrax, plague, or tularemia. Sudden ... Hospitalized children should be treated with a macrolide plus a beta-lactam inhibitor. ... Hospitalized children should be treated with a macrolide plus a beta-lactam inhibitor. In a bioterrorist attack, pulmonary ... Treatment with a macrolide plus a beta-lactam (high-dose amoxicillin or parenteral ceftriaxone [Rocephin]) should be considered ...
An example is the beta-lactam class of antibiotics (such as penicillin ). Also, the enzyme called lysozyme, which is found in ... the saliva and the tears of humans, attacks peptidoglycan by breaking the connection between the sugar molecules. This activity ...
... have also produced enzymes capable of attacking a wider spectrum of beta-lactam agents. The availability of newer beta-lactams ...
The hydroperoxy ligand deprotonates the amide which then closes the β-lactam ring by a nucleophilic attack at the thioaldehyde ... A second hydrogen transfer occurs, most likely producing an isopropyl radical which closes the thiazolidine ring by attacking ... which are different types of β-lactam antibiotics. This class of antibiotics is the most widely used. They act by inhibiting ...
... other beta-lactams, aminoglycosides, macrolides, quinolones, sulfonamides, and tetracyclines. A brief discussion of vancomycin ... Penicillin binding proteins, beta-lactams, and lactamases: offensives, attacks, and defensive countermeasures. Crit Rev ... Monobactams have a single beta-lactam core, distinguishing them from the other beta-lactam drugs [50]. Aztreonam is the only ... Like penicillins, the cephalosporins are beta-lactams in which the beta-lactam ring is joined to a dihydrothiazine ring. Their ...
We particularly focus on β-lactam/β-lactamase inhibitor combinations that could potentially be used to treat infections caused ... ATTACK). Recruiting. April, 2019. ... β-lactam-derived. Enmetazobactam. IC50 (nM). 360 a [44]. 1.1 × ... β-lactams are the most diverse and widely used group of antibiotics in clinical practice. The mechanism of action of β-lactams ... In addition to the above-mentioned β-lactam-derived inhibitors, other compounds with a β-lactam core are capable of inhibiting ...
Tick-borne relapsing fever (TBRF) is a bacterial infection attacking those who sleep in cabins in the mountains where rodents ... are plentiful.9 Treatments include penicillins, other beta-lactam antibiotics, tetracyclines, macrolides, and fluoroquinolones. ...
The reaction is initiated by radical attack at the N-C^sub 2^ bond, resulting in opening of the lactam ring (see Figure 1). ... Photomineralization of Lactam Ring-Pendant Polyvinylpyrrolidone at Titania/Water Interfaces. J. Photochem. Photobiol. A, 138, ...
Gram-positive bacteria are also much more susceptible to beta-lactam antibiotics, such as penicillin. ... and in fact the human body produces an enzyme called lysozyme which attacks the open peptidoglycan layer of Gram-positive ...
Identify and treat attacks early. If you act quickly, youre less likely to have a severe attack. You also wont need as much ... Penicillins belong to a class of antibacterial drugs called beta-lactam antibiotics. Although the mechanisms of the drugs vary ... generally they fight infections by attacking the walls of bacterial cells. In addition to penicillins, other beta-lactams more ... Severe asthma attacks can be life-threatening. Work with your doctor to determine what to do when your signs and symptoms ...
This form of attack is similar to how a group of antibiotics, called beta-lactams, work. These antibiotics include penicillin, ... Thomas Wood, now at Harvard Medical School, said: "The impact of VgrG2b on target cells mimics the action of beta-lactam ... These are bacteria devastated by attack with the toxic arrowhead. Credit: T.E. Wood et al. (2019) ...
While the double attack of extracts with antibiotics on different target sites was noted [73], the phytoconstituents coupled ... Zhao, W.H.; Hu, Z.Q.; Okubo, S.; Hara, Y.; Shimamura, T. Mechanism of synergy between epigallochatechin gallate and β-lactams ... reported that some phytochemicals can improve the in vitro activity of some peptidoglycan inhibiting antibiotics by attacking ... the ability of these antibacterial combinations to inhibit resistant bacteria showed that they have either attacked different ...
Avibactam Sodium: is a non-beta-lactam, beta-lactamase inhibitor. It is given with ceftazidime in the treatment of infections ... an anti-von Willebrand factor immunoglobulin monoclonal antibody that is under investigation for the treatment of acute attacks ... Tebipenem pivoxil: is a carbapenem beta-lactam antibacterial similar to imipenem. It is given as the prodrug tebipenem pivoxil ...
Twenty-five per cent of the Apis mellifera colonies in India perished after a severe attack of Varroa mite in 2005. The mites ... A Beta-lactam antibiotic, it is widely used in veterinary medicine for treatment and prevention of bacterial diseases. However ... Repeated exposure may cause allergic reactions, asthmatic attacks and other disorders.. ERYTHROMYCIN It is a Macrolide-class ... The broad spectrum antibiotic oxytetracycline is recommended only in case of a severe attack of European foul brood disease. ...
... presumably because of the high ring strain of the four-membered lactam ring (26). In avibactam, the site of attack by the ... 1997) Reversible acylation of elastase by gamma-lactam analogs of β-lactam inhibitors. Bioorg Med Chem Lett 7:2973-2978. ... to β-lactam antibiotics is the expression of various β-lactamase enzymes capable of hydrolyzing the β-lactam ring of β-lactam ... The non-β-lactam nature of the DBO scaffold prompted a detailed investigation into its mode of inhibition of the model β- ...
When this probe is attacked by β-lactamase, the probe core is cleaved, leading to the separation of the fluorophores and the ... A). The β-lactamase-activated fluorophore probe comprises a cleavable β-lactam core conjugated to 2 fluorophores (circled) that ... This construct was designed to mimic the enzymatic degradation properties of easily cleavable β-lactam antimicrobial drugs. ... Black, quenched fluorophore; blue, unquenched fluorophore turning fluorescent; green, β-lactam core; red, imipenem; purple, β- ...
The neuropathy is less 37-year-old to work within a multiple incubation, zithromax lowest generally any molecular attacks ... hiding beneath your person performance hepatic; acquisition lactam.. Clomid for sale, manufacturer jim was a initially driven ... Youll complete a such licensed somnolence research and review select your 2nd attack. Zinc for chlamydia azithromycinfor ...
... lactam carbonyl oxygen to facilitate nucleophilic attack and stabilise the negative charge developed on this oxygen in the ... An intrinsic property of binuclear metallo hydrolytic enzymes that depend on a metal-bound water both as the attacking ... co-ordinated water molecule so that the metal-bound hydroxide ion is a better nucleophile than water and is used to attack the ... lactam antibiotics such as penicillins, cephalosporins, carbapenems, and cephamycins. There are no clinically useful inhibitors ...
Hetacillin is a penicillin beta-lactam antibiotic used in the treatment of bacterial infections caused by susceptible, usually ... Ampicillin rapidly decomposes because of the intramolecular attack of the side chain amino group on the lactam ring. Hetacillin ... Lactams. Sub Class. Beta lactams. Direct Parent. Penicillins. Alternative Parents. Phenylimidazolidines / Alpha amino acids and ... Hetacillin is a beta-lactam antibiotic prodrug used to treat bacterial infections. In the body it gets converted to ampicillin. ...
  • β-Lactam β-Lactam antibiotics, which includes penicillins 2-Pyrrolidone 2-Piperidinone Caprolactam Spencer Knapp, Frank S. Gibson Organic Syntheses, Coll. (wikipedia.org)
  • This form of attack is similar to how a group of antibiotics, called beta-lactams, work. (eurekalert.org)
  • Dr Thomas Wood, now at Harvard Medical School, said: "The impact of VgrG2b on target cells mimics the action of beta-lactam antibiotics. (eurekalert.org)
  • β-lactams are the most diverse and widely used group of antibiotics in clinical practice. (mdpi.com)
  • Gram-positive bacteria are also much more susceptible to beta-lactam antibiotics, such as penicillin. (wikibooks.org)
  • The most common form of resistance to β-lactam antibiotics is the expression of various β-lactamase enzymes capable of hydrolyzing the β-lactam ring of β-lactam drugs, rendering them ineffective. (pnas.org)
  • In efforts to restore the efficacy of β-lactam antibiotics, β-lactamases have also been targeted with a variety of inhibitors ( 5 , 6 ). (pnas.org)
  • This shows how IPNS occupies an early and key role in the biosynthetic pathway of all of the penicillins and cephalosporins, which are different types of β-lactam antibiotics. (wikipedia.org)
  • β-Lactam antibiotics are extremely effective in disrupting the synthesis of the bacterial cell wall in both gram-positive and gram-negative bacteria. (asm.org)
  • Indeed, recent studies have demonstrated that deletion of the blaC gene, the only gene encoding a β-lactamase in M. tuberculosis , or inhibition of the encoded enzyme resulted in significantly increased sensitivity to β-lactam antibiotics. (asm.org)
  • Over the past 3 decades, many other potent β-lactam antibiotics, such as cephems, monobactams, and carbapenems, have been developed and are currently being utilized to treat a wide range of bacterial infections. (asm.org)
  • In fact, the high efficacy, high specificity, and low rate of adverse reactions make β-lactam antibiotics the most prescribed antimicrobial agents worldwide ( 12 ). (asm.org)
  • All β-lactam antibiotics show structural mimicry to the natural substrates of the bacterial dd -transpeptidases. (asm.org)
  • Inhibition of dd -transpeptidases by β-lactam antibiotics leads to disruption of the synthesis of the bacteria's cell wall ( 13 ). (asm.org)
  • β-Lactamases inactivate β-lactam antibiotics by efficiently hydrolyzing the amide group of the β-lactam ring, which is the prevalent mechanism of bacterial resistance to β-lactam antibiotics ( 13 ). (asm.org)
  • There have been few studies on the antitubercular effect of β-lactam antibiotics, probably due to the early discovery that Mycobacterium tuberculosis possesses intrinsic resistance to these antibiotics ( 25 ). (asm.org)
  • β-lactams and glycopeptides, powerful bactericidal antibiotics, interfere with the last steps of peptidoglycan synthesis. (wordpress.com)
  • β-Lactams such as the penicillins remain a very important group of antibiotics for the treatment of a wide variety of infections. (aspetjournals.org)
  • The expression of β-lactamases is the main mechanism of bacterial resistance against β-lactam antibiotics. (asm.org)
  • These enzymes are refractive to clinically employed lactamase inhibitors ( 1 ) and have a particular relevance in the clinical setting as they can hydrolyze a broad spectrum of β-lactam substrates, being able to inactivate carbapenems, the "last-resort" antibiotics in antibacterial therapy ( 6 ). (asm.org)
  • 2) Page, M. I. The Mechanisms of Reactions of â-Lactam Antibiotics. (hud.ac.uk)
  • Page, M. I. The Mechanism of Reactions of â-Lactam Antibiotics. (hud.ac.uk)
  • Streptomyces clavuligerous β -lactam synthetase ( β -LS) and Pectobacterium carotorova carbapenam synthetase (CPS) 1 catalyze formation of the corresponding β -lactam rings in the clinically important β -lactamase inhibitor clavulanic acid ( 4 ) and (5 R )-carbapenem-3-carboxylic acid ( 5 ), which is believed to be representative of the potent, broad spectrum carbapenem class of antibiotics. (pubmedcentralcanada.ca)
  • This remarkable polymer cell wall called peptidoglycan, given its basic composition of sugars and amino acids, is well known for being a major target of beta-lactam antibiotics such as Penicillin. (eurekalert.org)
  • In the following study, we came up with and validated a prompt, sensitive and precise method for the simultaneous determination of 56 antimicrobial drugs (tetracyclines, sulfonamides, β-lactams, macrolides and quinolones) using the ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). This method was implemented with success to determine antibiotics in samples collected from four wastewater treatment plants and five coasts in Tunisia. (environmental-expert.com)
  • The lecture Other Approaches to Beta Lactamase Issue - Beta Lactam Antibiotics by Adam Le Gresley, PhD is from the course Medical Chemistry. (lecturio.com)
  • Penicillin antibiotics need to attack the cell wall in order to be effective. (thecattlesite.com)
  • For gram-negative infections, the penicillin-type antibiotics, also called beta lactams, cannot get to the cell wall," describes Dr. Fox. (thecattlesite.com)
  • they only have a cell membrane, making them much more resistant to antibiotics because there's no cell wall to attack. (thecattlesite.com)
  • The most common mechanisms of resistance to β-lactam antibiotics in Gram negative bacteria is the hydrolysis of the antibiotics by a group of enzymes collectively called β-lactamases. (bcm.edu)
  • In contrast to Gram negatives, the most prevalent mechanism of β-lactam resistance in the Gram positive bacteria Staphylococcus aureus is the production of PBP2a, which is able to avoid the inhibitory effects of the antibiotics. (bcm.edu)
  • This is the means by which methicillin-resistance S. aureus (MRSA) is able to persist despite treatment with multiple β-lactam antibiotics. (bcm.edu)
  • Previous research in the Palzkill lab found that the protein BLIP-II (β-lactamase inhibitory protein) was able to weakly bind and inhibit PBP2a, thus making the S. aureus susceptible to β-lactam antibiotics. (bcm.edu)
  • b ) A representation of the van der Waals surface of NDM-1 shows that the substrate-binding groove on both sides of the metal ions is large enough to accommodate sizeable ligands, suggesting that β--lactam antibiotics carrying very large substituent groups could still be bound and hydrolysed by NDM-1. (nih.gov)
  • The point of variation between the penicillin-derived β--lactams is indicated by arrow 1 and the main point of variation in the carbepenem antibiotics is shown by arrow 2, both of which point into the large substrate-binding groove. (nih.gov)
  • Penicillin and amoxicillin are both beta lactam antibiotics, and kill certain types of bacteria by attacking the bacteria's cell walls and not letting them synthesize the components to make new cell walls. (reference.com)
  • Our research offers steps toward the design of new antibiotics that attack a previously untargeted bacterial enzyme,' says Townsend. (infectioncontroltoday.com)
  • At the root of their investigation, Lamichhane says, is the fact than more than half of antibiotics prescribed today are of a class called beta-lactams, which work by interrupting the function of the DD-transpeptidase enzyme that creates bacterial cell walls. (infectioncontroltoday.com)
  • By analyzing the enzyme's structure, Johns Hopkins researchers were able to design new compounds in the carbapenem group, a subclass of the beta-lactam antibiotics that bind to the LD-transpeptidase wall-building enzyme and stop its function. (infectioncontroltoday.com)
  • MRSA (Methicillin-Resistant Staphylococcus aureus ) is a strain of Staphylococcus aureus bacteria that has developed resistance to an entire class of antibiotics (called beta lactams), including methicillin, penicillin, amoxicillin, and oxacillin. (bioedonline.org)
  • It is among a group of drugs known as beta-lactam antibiotics because they are not sensitive to beta-lactam, an enzyme some bacteria can produce to resist antibiotic therapy. (wisegeek.com)
  • If a patient has an infection that does not appear to be responding to regular antibiotic drugs, beta-lactam antibiotics can be part of treatment, as they will be effective even against bacteria using this enzyme in their defense. (wisegeek.com)
  • In the hundreds of millions of years that antibiotics have been produced by some subsets of bacteria and fungi to act on their neighbors, evolutionary pressure has been at work for the bacteria under attack to devise resistance mechanisms to survive. (asmscience.org)
  • Over time, MRSA staph bacteria have developed resistance to a family of antibiotics known as beta lactams, which includes methicillin, penicillin, oxacillin, and amoxicillin. (bioedonline.org)
  • Enterococci have intrinsic resistance to most β-lactam antibiotics (including carbapenems) due to the low affinity of their penicillin-binding proteins. (derangedphysiology.com)
  • To this day, the pharmacology of beta-lactam antibiotics has clearly bore out an excellent safety and efficacy profile. (pharmafactz.com)
  • However, as we have said earlier, some species of bacteria produce beta-lactamase which effectively disrupts the activity of beta-lactam antibiotics. (mypetneedsthat.com)
  • Both transpeptidase and carboxypeptidase activities of PBPs occur at the d -Ala- d -Ala terminus of a murein precursor containing a disaccharide pentapeptide comprising N -acetylglucosamine and N -acetyl-muramic acid- l -Ala- d -Glu- l -Lys- d -Ala- d -Ala. β-Lactam antibiotics inhibit these enzymes by competing with the pentapeptide precursor for binding to the active site of the enzyme. (asm.org)
  • In vitro data on purified recombinant S. aureus PBP4 suggest that it is a β-lactamase and is not trapped as an acyl intermediate with β-lactam antibiotics. (asm.org)
  • The carboxypeptidase domain of PBPs is the target for β-lactam antibiotics in susceptible staphylococci (with penicillin MICs as low as 1 μg/ml). (asm.org)
  • Beta-lactam antibiotics should not be used: To decrease localised hyperpigmentation such as allergy, autoimmune disease or an abscess or other decision making based on the port site placements for laparoscopic hernia repairs, and for the caudate nucleus and putamen to substantia nigra and ventral striatum of patients with acute chest pain is present in erythrocytes. (yogachicago.com)
  • Physicochemical properties of amphoteric β-lactam antibiotics. (elsevier.com)
  • it has been confirmed that both antibiotics undergo self-aminolysis in solution through a nucleophilic attack of the free side-chain amino group in one molecule upon the β-lactam bond of a second molecule, forming a dimer. (elsevier.com)
  • Since the degradation rates of cefaclor and cefatrizine were found to be larger than those of other amino-β-lactam antibiotics, the second-order degradation rate process should be considered in the analysis of their in situ intestinal absorption rates at high concentrations. (elsevier.com)
  • Resistance to the β-lactams primarily occurs through the horizontal transfer of β-lactamase genes contained on plasmids ( 9 ). (asm.org)
  • Resistance to β-lactams is of major concern in the treatment of bacterial infections. (wordpress.com)
  • Metallo-beta-lactamases (MBLs) are broad-spectrum, Zn(II)-dependent lactamases able to confer resistance to virtually every β-lactam antibiotic currently available. (asm.org)
  • Resistance to beta-lactams comes in many forms. (coursera.org)
  • Most were submitted owing to unusual resistance and there was a strong current bias towards referral of isolates suspected of carbapenem resistance, though a few were sent because they were unusually susceptible, were resistant to non-β-lactam agents or because the sender had obtained discrepant results between different test methods. (deepdyve.com)
  • While the antitubercular drug rifampin and the carbapenem version of the β-lactam imipenem are listed in this chapter, representative brand names are also indicated, as well as infections for which these drugs have been utilized and where clinically significant resistance had been detected. (asmscience.org)
  • Acquisition of a metallo-β-lactamase gene will invariably mediate broad-spectrum β-lactam resistance in P. aeruginosa , but the level of in vitro resistance in Acinetobacter spp. (asm.org)
  • Reports of resistance vary, but a general consensus appears to prevail that quinolone and broad-spectrum β-lactam resistance is increasing in members of the family Enterobacteriaceae and Acinetobacter spp. (asm.org)
  • Gram-negative bacteria have at their disposal a plethora of resistance mechanisms that they can sequester and/or evince, eluding the actions of carbapenems and other β-lactams. (asm.org)
  • MUSIC] Welcome to this video lecture on resistance to beta-lactam in Escherichia coli, with a particular focus on ESBL, AmpC and carbapenemases. (coursera.org)
  • During this presentation, I will explain what are the mechanism of beta-lactam resistance in Escherichia coli, what are ESBL, AmpC and carbopenimases and finally, how do we detect them? (coursera.org)
  • Achiral ketenes and imines, in the presence of a chiral nucleophilic catalyst, are allowed to react to make β-lactams in high yields, enantioselectivities, and diastereoselectivities. (wikipedia.org)
  • Chiral ketene enolate formation via nucleophilic activation by the cinchona alkaloid facilitates enantioselective and diastereoselective β-lactam synthesis. (wikipedia.org)
  • Subsequent ring closure leads to the formation of the β-lactam and the regeneration of the chiral nucleophilic organocatalyst. (wikipedia.org)
  • Lactams form from intramolecular attack of linear acyl derivatives from the nucleophilic abstraction reaction. (wikipedia.org)
  • The hydroperoxy ligand deprotonates the amide which then closes the β-lactam ring by a nucleophilic attack at the thioaldehyde carbon. (wikipedia.org)
  • Nucleophilic attack of a side chain pyridine nitrogen atom on the C6 atom of the resultant imine yielded a bicyclic aromatic system which helps to stabilize the acyl enzyme to hydrolysis. (nih.gov)
  • The nonplanar butterfly shape of the penicillin molecule ( 3 ) was expected to reduce amide-resonance and thus increase the susceptibility of the carbonyl group to nucleophilic attack, compared with normal, planar amides [ 1 ]. (hindawi.com)
  • Another interesting difference between nucleophilic substitution in penicillins and peptides/amides is the preferred direction of attack and the geometry of the initially formed tetrahedral intermediate. (hindawi.com)
  • It is usually assumed that nucleophilic attack on the carbonyl carbon of a planar peptide will generate a tetrahedral intermediate with the lone pair on nitrogen anti to the incoming nucleophile, ( 6 ), ( 7 ). (hindawi.com)
  • Pathway 2: rearrangement of BP ( 1 ) to PA ( 2 ) followed by nucleophilic attack on lysine residues to form diastereoisomeric adducts ( 3 ) and ( 4 ). (aspetjournals.org)
  • MBLs are metal-dependent hydrolases which generally use Zn(II) as a Lewis acid to activate a water molecule for the nucleophilic attack. (asm.org)
  • N-Acyl -sultams undergo S-N rather than C-N fission, although -alkenyl substituents direct nucleophilic attack to the acyl center. (hud.ac.uk)
  • On aromatic azaheterocyclic compounds, it catalyzes the oxidation of relatively electrophilic carbons adjacent to the nitrogen to generate lactam metabolites, with the molybdopterin cofactor participating in a nucleophilic attack on the electrophilic carbon. (aspetjournals.org)
  • β -Lactam-synthesizing enzymes carbapenam synthetase (CPS) and β -lactam synthetase ( β -LS) are evolutionarily linked to a common ancestor, asparagine synthetase B (AS-B). These three relatives catalyze substrate acyl-adenylation and nucleophilic acyl substitution by either an external (AS-B) or internal (CPS, β -LS) nitrogen source. (pubmedcentralcanada.ca)
  • There are two broad classes of β-lactamases: serine-β-lactamases, which use a nucleophilic serine proceed through a covalent intermediate, and metallo-β-lactamases, which catalyze a direct attack of the water on the β-lactam ring. (bcm.edu)
  • Calculations carried out at the B3LYP/6-31+G(d) level of theory also support that nucleophilic attack by water takes place at the exocyclic carbon rather than at the â-lactam carbonyl carbon of the iminium ion. (open.ac.uk)
  • Formation of structures of N-(sianometil) nornikotin obtained from nucleophilic attack by cyanide ion on methyl iminium intermediate types. (blogspot.com)
  • Unlike typical tertiary amides, the carbonyl group of the strained four-membered ring is very reactive and susceptible to nucleophilic attack. (pharmafactz.com)
  • At neutral pH, cefaclor was degraded via intramolecular nucleophilic attack of the α-amino group on the β-lactam moiety. (elsevier.com)
  • The three inhibitors approved for clinical use are clavulanic acid, tazobactam, and sulbactam, all of which contain a β-lactam core. (pnas.org)
  • A shared mechanistic feature of the marketed β-lactam-based inhibitors is their reaction with the serine enzymes to form a covalent acyl-enzyme intermediate. (pnas.org)
  • Originally designed to combat class A serine β-lactamase enzymes such as TEM-1, the clinical use of β-lactam-based inhibitors has been diminished by the emergence of enzymes against which they are ineffective. (pnas.org)
  • Cation-π Control of Regiochemistry of Intramolecular Schmidt Reactions en Route to Bridged Bicyclic Lactams" (Communication). (wikipedia.org)
  • A highly enantioselective Ir(III)-catalyzed intramolecular C(sp 3 )-H amidation reaction of dioxazolone substrates provides optically enriched γ-lactams using an α-amino-acid-based chiral ligand. (organic-chemistry.org)
  • A Ru-catalyzed enantioselective annulation of 1,4,2-dioxazol-5-ones provides γ-lactams in good yield and high ee via intramolecular carbonylnitrene C-H insertion. (organic-chemistry.org)
  • Ir catalysis achieves a lactam synthesis directly from lactones and amines via aminolysis of lactone, N -alkylation of amine with hydroxyamide, and intramolecular transamidation of aminoamide. (organic-chemistry.org)
  • Ampicillin rapidly decomposes because of the intramolecular attack of the side chain amino group on the lactam ring. (drugbank.ca)
  • The lactam arising by the formal intramolecular condensation of the amino and carboxy groups of gamm -aminobutyric acid (GABA). (chemicalbook.com)
  • Our data show that the carbapenems successfully treated TB infections alone by attacking the right enzyme,' says Lamichhane. (infectioncontroltoday.com)
  • Evaluation of the elimination reactions performed with lactam 4 . (hindawi.com)
  • β-Sultams are reactive sulfonyl analogues of -lactams and show enormous rate enhancements over analogous reactions of sulfonamides. (hud.ac.uk)
  • 2-Pyrrolidone undergoes the reactions of a typical lactam, e.g. ring opening, attack on the carbonyl group, and replacement of hydrogens alpha to the carbonyl group. (chemicalbook.com)
  • Hetacillin is a penicillin beta-lactam antibiotic used in the treatment of bacterial infections caused by susceptible, usually gram-positive, organisms. (drugbank.ca)
  • Of the two species, E.faecium is the more β-lactam-resistant, whereas E.faecalis is frequently susceptible to ampicillin. (derangedphysiology.com)
  • Hetacillin is a beta-lactam antibiotic prodrug used to treat bacterial infections. (drugbank.ca)
  • MRSA has outfoxed every beta-lactam antibiotic, including methicillin, penicillin and amoxicillin. (fiercebiotech.com)
  • a ) An ampicillin molecule modelled into the active site of NDM-1 shows that the shared catalytic water molecule is ideally positioned to attack the β-lactam carbonyl group, as indicated by the arrow. (nih.gov)
  • An intrinsic property of binuclear metallo hydrolytic enzymes that depend on a metal-bound water both as the attacking nucleophile and as a ligand for the second metal-ion is that this water molecule, which is consumed during hydrolysis of the substrate, has to be replaced to maintain the catalytic cycle. (hindawi.com)
  • These enzymes catalyze the hydrolysis of the amide bond in the β-lactam ring characteristic of this family of drugs ( 1 - 5 ). (asm.org)
  • The pH-independent hydrolysis involves rate-limiting alkyl C-O fission and formation of an exocyclic â-lactam iminum ion. (open.ac.uk)
  • The basecatalyzed hydrolysis involves rate-limiting hydroxide attack at the ester carbonyl carbon. (open.ac.uk)
  • Specifically, the hydrolysis reaction catalyzed by CTX-M β-lactamase proceeds through a pre-covalent complex, a high-energy tetrahedral acylation intermediate, a low-energy acyl-enzyme complex, a high-energy tetrahedral deacylation intermediate after attack via a catalytic water, and lastly, the hydrolyzed β-lactam ring product which is released from the enzyme complex. (usf.edu)
  • In the case of the β-lactam ring, amide resonance is diminished. (pharmafactz.com)
  • This construct was designed to mimic the enzymatic degradation properties of easily cleavable β-lactam antimicrobial drugs. (cdc.gov)
  • These are bacteria devastated by attack with the toxic arrowhead. (eurekalert.org)
  • Gram-positive infections are generally less severe because the human body does not contain peptidoglycan, and in fact the human body produces an enzyme called lysozyme which attacks the open peptidoglycan layer of Gram-positive bacteria. (wikibooks.org)
  • A significant increase in the number of β-lactam-resistant strains of pathogenic bacteria has been reported over the past few years ( 35 ). (asm.org)
  • The essential functions of peptidoglycan and its confinement to bacteria make it a perfect target for attacking these organisms. (wordpress.com)
  • Bacteria are surrounded by a mesh-like structure which, similar to an external skeleton, defines the cell shape and provides protection against external attacks. (eurekalert.org)
  • They would have allowed ancient bacteria to shrug off many modern drugs such as tetracyclines, beta-lactams and vancomycin. (discovermagazine.com)
  • The antibiotic works by attacking the process bacteria use to synthesize cell walls. (wisegeek.com)
  • Clavamox is considered as a beta-lactam broad spectrum antibiotic, owing to its action in negating the effects of beta-lactamase produced by bacteria. (mypetneedsthat.com)
  • An Al(OTf) 3 -catalyzed cascade cyclization and ionic hydrogenation reaction of nitrogen substituted ketoamides enables an efficient and versatile synthesis of N -substituted lactams, pyrrolindinones, piperidones, and structurally related heterocycles in good yields. (organic-chemistry.org)
  • The mechanism for the acid-catalyzed pathway involves a preequilibrium protonation, probably at the beta-lactam nitrogen, followed by rate-limiting alkyl C-O fission with formation of an exocyclic iminum ion. (open.ac.uk)
  • These results imply formation of a â-lactam system containing a positively charged amide nitrogen atom that hydrolyzes via a pathway that preserves the â-lactam structure in the product and provide further evidence that cleavage of the â-lactam C-N bond is not as facile as is commonly imagined. (open.ac.uk)
  • CTX-M β-lactamases use a catalytic serine to hydrolyze the β-lactam ring. (usf.edu)
  • Their clinical significance is further embellished by their ability to hydrolyze all β-lactams and by the fact that there is currently no clinical inhibitor, nor is there likely to be for the foreseeable future. (asm.org)
  • Unlike the Staudinger β-lactam synthesis, the umpolung ketene in the Lectka β-lactam synthesis behaves as the nucleophile rather than the electrophile. (wikipedia.org)
  • General synthetic methods exist for the organic synthesis of lactams. (wikipedia.org)
  • The mechanism of action of β-lactams is based on binding and blocking the penicillin binding proteins (PBPs), which are involved in the final steps of cell wall synthesis [ 1 , 2 , 3 ]. (mdpi.com)
  • A lactam is a cyclic amide, formally derived from an amino alkanoic acid. (wikipedia.org)
  • Greek prefixes in alphabetical order indicate ring size: α-Lactam (3-atom rings) β-Lactam (4-atom rings) γ-Lactam (5-atom rings) δ-Lactam (6-atom rings) ε-Lactam (7-atom rings) This ring-size nomenclature stems from the fact that a hydrolyzed α-Lactam leads to an α-amino acid and a β-Lactam to a β-amino acid, etc. (wikipedia.org)
  • Lactams form from cyclisation of amino acids. (wikipedia.org)
  • γ-Amino-β-hydroxy amide products derived from a diastereoselective addition to N -diphenylphosphinyl imines can be efficiently converted to γ-lactams. (organic-chemistry.org)
  • Pathway 1: direct binding of BP ( 1 ) with epsilon amino groups of lysine residues by opening of the β-lactam ring. (aspetjournals.org)
  • Based on both sequence and structure homology ( 4 , 6 ), these β -lactam-forming enzymes show evolutionary roots in the broadly distributed asparagine synthetases, class B (AS-B), which convert the essential amino acid aspartate to asparagine. (pubmedcentralcanada.ca)
  • Crystal structures of PAH from Streptomyces clavuligerus (at 1.75 A and 2.45 A resolution, where 1 A=0.1 nm) imply how it binds beta-lactams rather than the amino acid substrate of the arginases from which it evolved. (rcsb.org)
  • We particularly focus on β-lactam/β-lactamase inhibitor combinations that could potentially be used to treat infections caused by carbapenemase-producer pathogens of critical priority. (mdpi.com)
  • Also, the enzyme called lysozyme, which is found in the saliva and the tears of humans, attacks peptidoglycan by breaking the connection between the sugar molecules. (encyclopedia.com)
  • The availability of newer beta-lactams may be conducive to the development of such beta-lactamases, in which chromosomal and newer plasmid derivatives that may or may not contain the AmpC gene are selected. (nih.gov)
  • A N -heterocyclic carbene catalyzed formal [3 + 2] annulation of enals with 2-aminoacrylates provides various γ-lactam derivatives in good yields with excellent diastereo- and enantioselectivities. (organic-chemistry.org)
  • E.faecium attacks debilitated patients, is more antibiotic-resistant in general, and specifically it is usually vancomycin-resistant. (derangedphysiology.com)
  • In a bioterrorist attack, pulmonary illness may result from the organisms that cause anthrax, plague, or tularemia. (aafp.org)
  • Avibactam is a β-lactamase inhibitor that is in clinical development, combined with β-lactam partners, for the treatment of bacterial infections comprising Gram-negative organisms. (pnas.org)
  • The targets of β-lactams were identified as penicillin-binding proteins (PBPs), and multiple PBPs with different affinities for β-lactams are generally present in the cell envelope. (wordpress.com)
  • Therefore, the protective capability of the inclusion nano-Complex formed between the sodium salt of poly(maleic acid- alt -octadecene) and a β-lactam drug (ampicillin trihydrate) on the chemical, enzymatic and biological degradation was evaluated. (preprints.org)
  • The β -lactam-containing secondary metabolites, most widely known for their antibacterial properties, are an instructive example of this evolutionary process. (pubmedcentralcanada.ca)
  • Most of the in vivo metabolites of nicotine are konitin lactams. (blogspot.com)
  • the electrophilic acyl center is thus displaced from the point of hydrolytic attack. (rcsb.org)
  • A second hydrogen transfer occurs, most likely producing an isopropyl radical which closes the thiazolidine ring by attacking the thiolate sulfur atom. (wikipedia.org)
  • TEM-1 and SHV-1) have also produced enzymes capable of attacking a wider spectrum of beta-lactam agents. (nih.gov)
  • As new β-lactams have been introduced into clinical use, a changing landscape of β-lactamases has been selected and disseminated. (pnas.org)
  • Mobashery, S. Molecular Bases for Interactions between â-Lactam Antiobiotics and â-Lactamases. (hud.ac.uk)
  • Introduction Ceftazidime/avibactam is the first β-lactam/diazabicyclooctane (DBO) β-lactamase inhibitor combination to enter clinical use.1 Avibactam inhibits most ceftazidime-hydrolysing Class A and C β-lactamases, including KPC carbapenemases as well as ESBLs and AmpC enzymes;2,3 ceftazidime is anyway stable to OXA-48-like carbapenemases4 and has good antipseudomonal activity. (deepdyve.com)
  • A mainstay for treatment of Gram-negative infections is the β-lactam classes of drugs. (pnas.org)
  • Penicillin G was the first β-lactam antibiotic discovered, and it was used extensively to treat bacterial infections from the 1940s to 1960s ( 5 ). (asm.org)
  • The tertiary amine contained within the quinuclidine can act as a nucleophile that attacks the most electrophilic carbon of the ketene to promote the formation of β-lactams. (wikipedia.org)
  • The chiral ketene enolate nucleophile attacks electrophilic carbon of the imine group. (wikipedia.org)
  • A gold-catalyzed tandem cycloisomerization/oxidation of homopropargyl amides provides ready access to synthetically useful chiral γ-lactams with excellent ee by combining the chiral tert -butylsulfinimine chemistry and gold catalysis. (organic-chemistry.org)
  • Upon Ir catalysis, N -benzoyloxyamides serve as efficient acylnitrenoid precursors to afford γ-lactams. (organic-chemistry.org)
  • A compound derived from this deep-water marine sponge could lead to an alternative means to attack the antibiotic-resistant bacterium, MRSA. (fiercebiotech.com)
  • These results suggest a promissory capability of this polymer to protect the β-lactam drugs against chemical, enzymatic and biological degradation. (preprints.org)
  • Lactams form by the acid-catalyzed rearrangement of oximes in the Beckmann rearrangement. (wikipedia.org)
  • This iminium ion is then trapped by water at the exocyclic iminium carbon atom, rather than at the â-lactam carbonyl carbon atom, to form the corresponding N-hydroxymethylazetidin-2-ones. (open.ac.uk)
  • As observed for the arginases, each PAH monomer consists of a core of beta-strands surrounded by alpha-helices, and its active site contains a di-Mn2+ centre with a bridging water molecule responsible for hydrolytic attack on to the guanidino group of the substrate. (rcsb.org)
  • The protonated isocyanate is attacked by water forming carbamate 4, which after deprotonation loses carbon dioxide to the amine. (wikipedia.org)
  • Lactams form from cyclic ketones and hydrazoic acid in the Schmidt reaction. (wikipedia.org)
  • Lactams form by copper-catalyzed 1,3-dipolar cycloaddition of alkynes and nitrones in the Kinugasa reaction Diels-Alder reaction between cyclopentadiene and chlorosulfonyl isocyanate (CSI) can be utilized to obtain both β- as well as γ-lactam. (wikipedia.org)
  • A quick, efficient, one-pot, BF 3 OEt 2 -mediated reaction of various substituted arenes with azido alkanoic acid chlorides affords substituted N -aryl lactams in good to excellent yields at room temperature. (organic-chemistry.org)
  • This convenient reaction offers a step-economic route to γ-lactams. (organic-chemistry.org)
  • However, [ 32 P]PP i -ATP exchange assays demonstrated Y345A and E380A undergo the first half-reaction, with the remaining active mutants showing decreased forward commitment to β -lactam cyclization. (pubmedcentralcanada.ca)
  • As a result of the attachment of amoxicillin to the bacterial cell wall, the microorganism can no longer build a formidable cell wall which should protect it from attacks by immune system cells. (mypetneedsthat.com)
  • pH-rate profiles of CPS and β -LS supported the importance of a Tyr-Glu dyad in β -lactam formation and suggested its reverse protonation in β -LS. (pubmedcentralcanada.ca)
  • 260/78 TF ll/l97l Blanchard et al 210/500 Primary ExaminerFrank A. Spear, Jr. Assistant ExaminerFerris H. Lander [57] ABSTRACT Permselective membranes are prepared from novel synthetic organic aromatic polyamides of the formula The membranes are useful in separating components of fluid mixtures or solution such as water containing dissolved salts or lactam. (google.com)