A change from planar to elliptic polarization when an initially plane-polarized light wave traverses an optically active medium. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
The level of protein structure in which regular hydrogen-bond interactions within contiguous stretches of polypeptide chain give rise to alpha helices, beta strands (which align to form beta sheets) or other types of coils. This is the first folding level of protein conformation.
Any of the covalently closed DNA molecules found in bacteria, many viruses, mitochondria, plastids, and plasmids. Small, polydisperse circular DNA's have also been observed in a number of eukaryotic organisms and are suggested to have homology with chromosomal DNA and the capacity to be inserted into, and excised from, chromosomal DNA. It is a fragment of DNA formed by a process of looping out and deletion, containing a constant region of the mu heavy chain and the 3'-part of the mu switch region. Circular DNA is a normal product of rearrangement among gene segments encoding the variable regions of immunoglobulin light and heavy chains, as well as the T-cell receptor. (Riger et al., Glossary of Genetics, 5th ed & Segen, Dictionary of Modern Medicine, 1992)
The characteristic 3-dimensional shape of a protein, including the secondary, supersecondary (motifs), tertiary (domains) and quaternary structure of the peptide chain. PROTEIN STRUCTURE, QUATERNARY describes the conformation assumed by multimeric proteins (aggregates of more than one polypeptide chain).
Determination of the spectra of ultraviolet absorption by specific molecules in gases or liquids, for example Cl2, SO2, NO2, CS2, ozone, mercury vapor, and various unsaturated compounds. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
Disruption of the non-covalent bonds and/or disulfide bonds responsible for maintaining the three-dimensional shape and activity of the native protein.
Measurement of the intensity and quality of fluorescence.
Processes involved in the formation of TERTIARY PROTEIN STRUCTURE.
The order of amino acids as they occur in a polypeptide chain. This is referred to as the primary structure of proteins. It is of fundamental importance in determining PROTEIN CONFORMATION.
Descriptions of specific amino acid, carbohydrate, or nucleotide sequences which have appeared in the published literature and/or are deposited in and maintained by databanks such as GENBANK, European Molecular Biology Laboratory (EMBL), National Biomedical Research Foundation (NBRF), or other sequence repositories.
A strong organic base existing primarily as guanidium ions at physiological pH. It is found in the urine as a normal product of protein metabolism. It is also used in laboratory research as a protein denaturant. (From Martindale, the Extra Pharmacopoeia, 30th ed and Merck Index, 12th ed) It is also used in the treatment of myasthenia and as a fluorescent probe in HPLC.
The method of measuring the dispersion of an optically active molecule to determine the relative magnitude of right- or left-handed components and sometimes structural features of the molecule.
A rigorously mathematical analysis of energy relationships (heat, work, temperature, and equilibrium). It describes systems whose states are determined by thermal parameters, such as temperature, in addition to mechanical and electromagnetic parameters. (From Hawley's Condensed Chemical Dictionary, 12th ed)
Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.
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).
A non-aqueous co-solvent that serves as tool to study protein folding. It is also used in various pharmaceutical, chemical and engineering applications.
The property of objects that determines the direction of heat flow when they are placed in direct thermal contact. The temperature is the energy of microscopic motions (vibrational and translational) of the particles of atoms.
The measurement of the amplitude of the components of a complex waveform throughout the frequency range of the waveform. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
The spatial arrangement of the atoms of a nucleic acid or polynucleotide that results in its characteristic 3-dimensional shape.
The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments.
Differential thermal analysis in which the sample compartment of the apparatus is a differential calorimeter, allowing an exact measure of the heat of transition independent of the specific heat, thermal conductivity, and other variables of the sample.
The normality of a solution with respect to HYDROGEN ions; H+. It is related to acidity measurements in most cases by pH = log 1/2[1/(H+)], where (H+) is the hydrogen ion concentration in gram equivalents per liter of solution. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
The rate dynamics in chemical or physical systems.
The parts of a macromolecule that directly participate in its specific combination with another molecule.
An essential amino acid that is necessary for normal growth in infants and for NITROGEN balance in adults. It is a precursor of INDOLE ALKALOIDS in plants. It is a precursor of SEROTONIN (hence its use as an antidepressant and sleep aid). It can be a precursor to NIACIN, albeit inefficiently, in mammals.
The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.
The level of protein structure in which combinations of secondary protein structures (alpha helices, beta sheets, loop regions, and motifs) pack together to form folded shapes called domains. Disulfide bridges between cysteines in two different parts of the polypeptide chain along with other interactions between the chains play a role in the formation and stabilization of tertiary structure. Small proteins usually consist of only one domain but larger proteins may contain a number of domains connected by segments of polypeptide chain which lack regular secondary structure.
A group of 13 or more deoxyribonucleotides in which the phosphate residues of each deoxyribonucleotide act as bridges in forming diester linkages between the deoxyribose moieties.
Members of the class of compounds composed of AMINO ACIDS joined together by peptide bonds between adjacent amino acids into linear, branched or cyclical structures. OLIGOPEPTIDES are composed of approximately 2-12 amino acids. Polypeptides are composed of approximately 13 or more amino acids. PROTEINS are linear polypeptides that are normally synthesized on RIBOSOMES.
A species of gram-negative, facultatively anaerobic, rod-shaped bacteria (GRAM-NEGATIVE FACULTATIVELY ANAEROBIC RODS) commonly found in the lower part of the intestine of warm-blooded animals. It is usually nonpathogenic, but some strains are known to produce DIARRHEA and pyogenic infections. Pathogenic strains (virotypes) are classified by their specific pathogenic mechanisms such as toxins (ENTEROTOXIGENIC ESCHERICHIA COLI), etc.
Proteins prepared by recombinant DNA technology.
A class of organic compounds which contain an anilino (phenylamino) group linked to a salt or ester of naphthalenesulfonic acid. They are frequently used as fluorescent dyes and sulfhydryl reagents.
Disruption of the secondary structure of nucleic acids by heat, extreme pH or chemical treatment. Double strand DNA is "melted" by dissociation of the non-covalent hydrogen bonds and hydrophobic interactions. Denatured DNA appears to be a single-stranded flexible structure. The effects of denaturation on RNA are similar though less pronounced and largely reversible.
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.
Spectrophotometry in the infrared region, usually for the purpose of chemical analysis through measurement of absorption spectra associated with rotational and vibrational energy levels of molecules. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
NMR spectroscopy on small- to medium-size biological macromolecules. This is often used for structural investigation of proteins and nucleic acids, and often involves more than one isotope.
The characteristic three-dimensional shape of a molecule.
Partial proteins formed by partial hydrolysis of complete proteins or generated through PROTEIN ENGINEERING techniques.
The homogeneous mixtures formed by the mixing of a solid, liquid, or gaseous substance (solute) with a liquid (the solvent), from which the dissolved substances can be recovered by physical processes. (From Grant & Hackh's Chemical Dictionary, 5th ed)
Presence of warmth or heat or a temperature notably higher than an accustomed norm.
The extent to which an enzyme retains its structural conformation or its activity when subjected to storage, isolation, and purification or various other physical or chemical manipulations, including proteolytic enzymes and heat.
Higher-order DNA and RNA structures formed from guanine-rich sequences. They are formed around a core of at least 2 stacked tetrads of hydrogen-bonded GUANINE bases. They can be formed from one two or four separate strands of DNA (or RNA) and can display a wide variety of topologies, which are a consequence of various combinations of strand direction, length, and sequence. (From Nucleic Acids Res. 2006;34(19):5402-15)
A spectroscopic technique in which a range of wavelengths is presented simultaneously with an interferometer and the spectrum is mathematically derived from the pattern thus obtained.
A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine).
The diversion of RADIATION (thermal, electromagnetic, or nuclear) from its original path as a result of interactions or collisions with atoms, molecules, or larger particles in the atmosphere or other media. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
A compound formed in the liver from ammonia produced by the deamination of amino acids. It is the principal end product of protein catabolism and constitutes about one half of the total urinary solids.
The ability of a protein to retain its structural conformation or its activity when subjected to physical or chemical manipulations.
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)
Centrifugation with a centrifuge that develops centrifugal fields of more than 100,000 times gravity. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
The sequence of PURINES and PYRIMIDINES in nucleic acids and polynucleotides. It is also called nucleotide sequence.
Domesticated bovine animals of the genus Bos, usually kept on a farm or ranch and used for the production of meat or dairy products or for heavy labor.
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.
A family of iminourea derivatives. The parent compound has been isolated from mushrooms, corn germ, rice hulls, mussels, earthworms, and turnip juice. Derivatives may have antiviral and antifungal properties.
The measurement of the quantity of heat involved in various processes, such as chemical reactions, changes of state, and formations of solutions, or in the determination of the heat capacities of substances. The fundamental unit of measurement is the joule or the calorie (4.184 joules). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
The protein components of a number of complexes, such as enzymes (APOENZYMES), ferritin (APOFERRITINS), or lipoproteins (APOLIPOPROTEINS).
Electrophoresis in which a polyacrylamide gel is used as the diffusion medium.
Conformational transitions of the shape of a protein to various unfolded states.
Particles consisting of aggregates of molecules held loosely together by secondary bonds. The surface of micelles are usually comprised of amphiphatic compounds that are oriented in a way that minimizes the energy of interaction between the micelle and its environment. Liquids that contain large numbers of suspended micelles are referred to as EMULSIONS.
A left-handed double helix of DNA. Its name derives from its narrow zigzag structure that is the least twisted and thinnest form of DNA. Z-DNA forming regions within the GENOME may play an important role in GENE EXPRESSION REGULATION.
Genetically engineered MUTAGENESIS at a specific site in the DNA molecule that introduces a base substitution, or an insertion or deletion.
Chromatography on non-ionic gels without regard to the mechanism of solute discrimination.
The process by which two molecules of the same chemical composition form a condensation product or polymer.
Theoretical representations that simulate the behavior or activity of chemical processes or phenomena; includes the use of mathematical equations, computers, and other electronic equipment.
A trypanocidal agent and possible antiviral agent that is widely used in experimental cell biology and biochemistry. Ethidium has several experimentally useful properties including binding to nucleic acids, noncompetitive inhibition of nicotinic acetylcholine receptors, and fluorescence among others. It is most commonly used as the bromide.
The reconstitution of a protein's activity following denaturation.
Analysis of the intensity of Raman scattering of monochromatic light as a function of frequency of the scattered light.
Devices for accelerating protons or electrons in closed orbits where the accelerating voltage and magnetic field strength varies (the accelerating voltage is held constant for electrons) in order to keep the orbit radius constant.
Chemical groups containing the covalent disulfide bonds -S-S-. The sulfur atoms can be bound to inorganic or organic moieties.
Proteins found in any species of bacterium.
The chemical and physical integrity of a pharmaceutical product.
The thermodynamic interaction between a substance and WATER.
Compounds and molecular complexes that consist of very large numbers of atoms and are generally over 500 kDa in size. In biological systems macromolecular substances usually can be visualized using ELECTRON MICROSCOPY and are distinguished from ORGANELLES by the lack of a membrane structure.
A technique applicable to the wide variety of substances which exhibit paramagnetism because of the magnetic moments of unpaired electrons. The spectra are useful for detection and identification, for determination of electron structure, for study of interactions between molecules, and for measurement of nuclear spins and moments. (From McGraw-Hill Encyclopedia of Science and Technology, 7th edition) Electron nuclear double resonance (ENDOR) spectroscopy is a variant of the technique which can give enhanced resolution. Electron spin resonance analysis can now be used in vivo, including imaging applications such as MAGNETIC RESONANCE IMAGING.
Liquids that dissolve other substances (solutes), generally solids, without any change in chemical composition, as, water containing sugar. (Grant & Hackh's Chemical Dictionary, 5th ed)
The characteristic 3-dimensional shape and arrangement of multimeric proteins (aggregates of more than one polypeptide chain).
Agents that are capable of inserting themselves between the successive bases in DNA, thus kinking, uncoiling or otherwise deforming it and therefore preventing its proper functioning. They are used in the study of DNA.
Artificial, single or multilaminar vesicles (made from lecithins or other lipids) that are used for the delivery of a variety of biological molecules or molecular complexes to cells, for example, drug delivery and gene transfer. They are also used to study membranes and membrane proteins.
A conjugated protein which is the oxygen-transporting pigment of muscle. It is made up of one globin polypeptide chain and one heme group.
The property of emitting radiation while being irradiated. The radiation emitted is usually of longer wavelength than that incident or absorbed, e.g., a substance can be irradiated with invisible radiation and emit visible light. X-ray fluorescence is used in diagnosis.
An anionic surfactant, usually a mixture of sodium alkyl sulfates, mainly the lauryl; lowers surface tension of aqueous solutions; used as fat emulsifier, wetting agent, detergent in cosmetics, pharmaceuticals and toothpastes; also as research tool in protein biochemistry.
The degree of similarity between sequences of amino acids. This information is useful for the analyzing genetic relatedness of proteins and species.
Organic compounds that generally contain an amino (-NH2) and a carboxyl (-COOH) group. Twenty alpha-amino acids are the subunits which are polymerized to form proteins.
A chemical reaction in which an electron is transferred from one molecule to another. The electron-donating molecule is the reducing agent or reductant; the electron-accepting molecule is the oxidizing agent or oxidant. Reducing and oxidizing agents function as conjugate reductant-oxidant pairs or redox pairs (Lehninger, Principles of Biochemistry, 1982, p471).
The determination of the concentration of a given component in solution (the analyte) by addition of a liquid reagent of known strength (the titrant) until an equivalence point is reached (when the reactants are present in stoichiometric proportions). Often an indicator is added to make the equivalence point visible (e.g., a change in color).
A group of 13 or more ribonucleotides in which the phosphate residues of each ribonucleotide act as bridges in forming diester linkages between the ribose moieties.
Globulins of milk obtained from the WHEY.
A major protein fraction of milk obtained from the WHEY.
Layers of lipid molecules which are two molecules thick. Bilayer systems are frequently studied as models of biological membranes.
The rotation of linearly polarized light as it passes through various media.
Microscopy using an electron beam, instead of light, to visualize the sample, thereby allowing much greater magnification. The interactions of ELECTRONS with specimens are used to provide information about the fine structure of that specimen. In TRANSMISSION ELECTRON MICROSCOPY the reactions of the electrons that are transmitted through the specimen are imaged. In SCANNING ELECTRON MICROSCOPY an electron beam falls at a non-normal angle on the specimen and the image is derived from the reactions occurring above the plane of the specimen.
The study of PHYSICAL PHENOMENA and PHYSICAL PROCESSES as applied to living things.
The sum of the weight of all the atoms in a molecule.
The color-furnishing portion of hemoglobin. It is found free in tissues and as the prosthetic group in many hemeproteins.
Conformational transitions of a protein from unfolded states to a more folded state.
Polymers made up of a few (2-20) nucleotides. In molecular genetics, they refer to a short sequence synthesized to match a region where a mutation is known to occur, and then used as a probe (OLIGONUCLEOTIDE PROBES). (Dorland, 28th ed)
A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.
The concentration of osmotically active particles in solution expressed in terms of osmoles of solute per liter of solution. Osmolality is expressed in terms of osmoles of solute per kilogram of solvent.
The insertion of recombinant DNA molecules from prokaryotic and/or eukaryotic sources into a replicating vehicle, such as a plasmid or virus vector, and the introduction of the resultant hybrid molecules into recipient cells without altering the viability of those cells.
The assembly of the QUATERNARY PROTEIN STRUCTURE of multimeric proteins (MULTIPROTEIN COMPLEXES) from their composite PROTEIN SUBUNITS.
The temperature at which a substance changes from one state or conformation of matter to another.
Any detectable and heritable change in the genetic material that causes a change in the GENOTYPE and which is transmitted to daughter cells and to succeeding generations.
The physical characteristics and processes of biological systems.
A clear, odorless, tasteless liquid that is essential for most animal and plant life and is an excellent solvent for many substances. The chemical formula is hydrogen oxide (H2O). (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
A low-energy attractive force between hydrogen and another element. It plays a major role in determining the properties of water, proteins, and other compounds.
The composition, conformation, and properties of atoms and molecules, and their reaction and interaction processes.
A synthetic phospholipid used in liposomes and lipid bilayers for the study of biological membranes.
The scattering of x-rays by matter, especially crystals, with accompanying variation in intensity due to interference effects. Analysis of the crystal structure of materials is performed by passing x-rays through them and registering the diffraction image of the rays (CRYSTALLOGRAPHY, X-RAY). (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
A molecule that binds to another molecule, used especially to refer to a small molecule that binds specifically to a larger molecule, e.g., an antigen binding to an antibody, a hormone or neurotransmitter binding to a receptor, or a substrate or allosteric effector binding to an enzyme. Ligands are also molecules that donate or accept a pair of electrons to form a coordinate covalent bond with the central metal atom of a coordination complex. (From Dorland, 27th ed)
That portion of the electromagnetic spectrum immediately below the visible range and extending into the x-ray frequencies. The longer wavelengths (near-UV or biotic or vital rays) are necessary for the endogenous synthesis of vitamin D and are also called antirachitic rays; the shorter, ionizing wavelengths (far-UV or abiotic or extravital rays) are viricidal, bactericidal, mutagenic, and carcinogenic and are used as disinfectants.
Basic polypeptide from the venom of the honey bee (Apis mellifera). It contains 26 amino acids, has cytolytic properties, causes contracture of muscle, releases histamine, and disrupts surface tension, probably due to lysis of cell and mitochondrial membranes.
Measurement of the polarization of fluorescent light from solutions or microscopic specimens. It is used to provide information concerning molecular size, shape, and conformation, molecular anisotropy, electronic energy transfer, molecular interaction, including dye and coenzyme binding, and the antigen-antibody reaction.
Procedures by which protein structure and function are changed or created in vitro by altering existing or synthesizing new structural genes that direct the synthesis of proteins with sought-after properties. Such procedures may include the design of MOLECULAR MODELS of proteins using COMPUTER GRAPHICS or other molecular modeling techniques; site-specific mutagenesis (MUTAGENESIS, SITE-SPECIFIC) of existing genes; and DIRECTED MOLECULAR EVOLUTION techniques to create new genes.
Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.
Extrachromosomal, usually CIRCULAR DNA molecules that are self-replicating and transferable from one organism to another. They are found in a variety of bacterial, archaeal, fungal, algal, and plant species. They are used in GENETIC ENGINEERING as CLONING VECTORS.
An isoform of DNA that occurs in an environment rich in SODIUM and POTASSIUM ions. It is a right-handed helix with 11 base pairs per turn, a pitch of 0.256 nm per base pair and a helical diameter of 2.3 nm.
An essential amino acid that is required for the production of HISTAMINE.
That portion of the electromagnetic spectrum in the visible, ultraviolet, and infrared range.
Polydeoxyribonucleotides made up of deoxyadenine nucleotides and thymine nucleotides. Present in DNA preparations isolated from crab species. Synthetic preparations have been used extensively in the study of DNA.
Substances produced from the reaction between acids and bases; compounds consisting of a metal (positive) and nonmetal (negative) radical. (Grant & Hackh's Chemical Dictionary, 5th ed)
Common name for the species Gallus gallus, the domestic fowl, in the family Phasianidae, order GALLIFORMES. It is descended from the red jungle fowl of SOUTHEAST ASIA.
A group of deoxyribonucleotides (up to 12) in which the phosphate residues of each deoxyribonucleotide act as bridges in forming diester linkages between the deoxyribose moieties.
The naturally occurring or experimentally induced replacement of one or more AMINO ACIDS in a protein with another. If a functionally equivalent amino acid is substituted, the protein may retain wild-type activity. Substitution may also diminish, enhance, or eliminate protein function. Experimentally induced substitution is often used to study enzyme activities and binding site properties.
An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.
The ability of a substance to be dissolved, i.e. to form a solution with another substance. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
A fibrous protein complex that consists of proteins folded into a specific cross beta-pleated sheet structure. This fibrillar structure has been found as an alternative folding pattern for a variety of functional proteins. Deposits of amyloid in the form of AMYLOID PLAQUES are associated with a variety of degenerative diseases. The amyloid structure has also been found in a number of functional proteins that are unrelated to disease.
The study of crystal structure using X-RAY DIFFRACTION techniques. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)
The arrangement of two or more amino acid or base sequences from an organism or organisms in such a way as to align areas of the sequences sharing common properties. The degree of relatedness or homology between the sequences is predicted computationally or statistically based on weights assigned to the elements aligned between the sequences. This in turn can serve as a potential indicator of the genetic relatedness between the organisms.
A serine endopeptidase that is formed from TRYPSINOGEN in the pancreas. It is converted into its active form by ENTEROPEPTIDASE in the small intestine. It catalyzes hydrolysis of the carboxyl group of either arginine or lysine. EC
A thiol-containing non-essential amino acid that is oxidized to form CYSTINE.
Large, hoofed mammals of the family EQUIDAE. Horses are active day and night with most of the day spent seeking and consuming food. Feeding peaks occur in the early morning and late afternoon, and there are several daily periods of rest.
A metallic element of atomic number 30 and atomic weight 65.38. It is a necessary trace element in the diet, forming an essential part of many enzymes, and playing an important role in protein synthesis and in cell division. Zinc deficiency is associated with ANEMIA, short stature, HYPOGONADISM, impaired WOUND HEALING, and geophagia. It is known by the symbol Zn.
A biosensing technique in which biomolecules capable of binding to specific analytes or ligands are first immobilized on one side of a metallic film. Light is then focused on the opposite side of the film to excite the surface plasmons, that is, the oscillations of free electrons propagating along the film's surface. The refractive index of light reflecting off this surface is measured. When the immobilized biomolecules are bound by their ligands, an alteration in surface plasmons on the opposite side of the film is created which is directly proportional to the change in bound, or adsorbed, mass. Binding is measured by changes in the refractive index. The technique is used to study biomolecular interactions, such as antigen-antibody binding.
A basic enzyme that is present in saliva, tears, egg white, and many animal fluids. It functions as an antibacterial agent. The enzyme catalyzes the hydrolysis of 1,4-beta-linkages between N-acetylmuramic acid and N-acetyl-D-glucosamine residues in peptidoglycan and between N-acetyl-D-glucosamine residues in chitodextrin. EC
The study of CHEMICAL PHENOMENA and processes in terms of the underlying PHYSICAL PHENOMENA and processes.
A type of scanning probe microscopy in which a probe systematically rides across the surface of a sample being scanned in a raster pattern. The vertical position is recorded as a spring attached to the probe rises and falls in response to peaks and valleys on the surface. These deflections produce a topographic map of the sample.
A major protein in the BLOOD. It is important in maintaining the colloidal osmotic pressure and transporting large organic molecules.
A serine endopeptidase secreted by the pancreas as its zymogen, CHYMOTRYPSINOGEN and carried in the pancreatic juice to the duodenum where it is activated by TRYPSIN. It selectively cleaves aromatic amino acids on the carboxyl side.
Linear POLYPEPTIDES that are synthesized on RIBOSOMES and may be further modified, crosslinked, cleaved, or assembled into complex proteins with several subunits. The specific sequence of AMINO ACIDS determines the shape the polypeptide will take, during PROTEIN FOLDING, and the function of the protein.
A brominating agent that replaces hydrogen atoms in benzylic or allylic positions. It is used in the oxidation of secondary alcohols to ketones and in controlled low-energy brominations. (From Miall's Dictionary of Chemistry, 5th ed; Hawley's Condensed Chemical Dictionary, 12th ed,).
A nitrogen-free class of lipids present in animal and particularly plant tissues and composed of one mole of glycerol and 1 or 2 moles of phosphatidic acid. Members of this group differ from one another in the nature of the fatty acids released on hydrolysis.
Derivatives of phosphatidic acids in which the phosphoric acid is bound in ester linkage to a choline moiety. Complete hydrolysis yields 1 mole of glycerol, phosphoric acid and choline and 2 moles of fatty acids.
The physical phenomena describing the structure and properties of atoms and molecules, and their reaction and interaction processes.
A group of compounds containing the porphin structure, four pyrrole rings connected by methine bridges in a cyclic configuration to which a variety of side chains are attached. The nature of the side chain is indicated by a prefix, as uroporphyrin, hematoporphyrin, etc. The porphyrins, in combination with iron, form the heme component in biologically significant compounds such as hemoglobin and myoglobin.
Toxins isolated from the venom of Laticauda semifasciata, a sea snake (Hydrophid); immunogenic, basic polypeptides of 62 amino acids, folded by four disulfide bonds, block neuromuscular end-plates irreversibly, thus causing paralysis and severe muscle damage; they are similar to Elapid neurotoxins.
A group of peptide antibiotics from BACILLUS brevis. Gramicidin C or S is a cyclic, ten-amino acid polypeptide and gramicidins A, B, D are linear. Gramicidin is one of the two principal components of TYROTHRICIN.
A trace element that is a component of vitamin B12. It has the atomic symbol Co, atomic number 27, and atomic weight 58.93. It is used in nuclear weapons, alloys, and pigments. Deficiency in animals leads to anemia; its excess in humans can lead to erythrocytosis.
The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.
Purifying or cleansing agents, usually salts of long-chain aliphatic bases or acids, that exert cleansing (oil-dissolving) and antimicrobial effects through a surface action that depends on possessing both hydrophilic and hydrophobic properties.
A group of guanine ribonucleotides in which the phosphate residues of each guanine ribonucleotide act as bridges in forming diester linkages between the ribose moieties.
Proteins produced from GENES that have acquired MUTATIONS.
A ubiquitous sodium salt that is commonly used to season food.
The transfer of energy of a given form among different scales of motion. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed). It includes the transfer of kinetic energy and the transfer of chemical energy. The transfer of chemical energy from one molecule to another depends on proximity of molecules so it is often used as in techniques to measure distance such as the use of FORSTER RESONANCE ENERGY TRANSFER.
Inorganic or organic compounds that contain divalent iron.
Small cationic peptides that are an important component, in most species, of early innate and induced defenses against invading microbes. In animals they are found on mucosal surfaces, within phagocytic granules, and on the surface of the body. They are also found in insects and plants. Among others, this group includes the DEFENSINS, protegrins, tachyplesins, and thionins. They displace DIVALENT CATIONS from phosphate groups of MEMBRANE LIPIDS leading to disruption of the membrane.
The accumulation of an electric charge on a object
A non-crystalline form of silicon oxide that has absorptive properties. It is commonly used as a desiccating agent and as a stationary phase for CHROMATOGRAPHY. The fully hydrated form of silica gel has distinct properties and is referred to as SILICIC ACID.
A representation, generally small in scale, to show the structure, construction, or appearance of something. (From Random House Unabridged Dictionary, 2d ed)
Proteins that have one or more tightly bound metal ions forming part of their structure. (Dorland, 28th ed)
Commonly observed structural components of proteins formed by simple combinations of adjacent secondary structures. A commonly observed structure may be composed of a CONSERVED SEQUENCE which can be represented by a CONSENSUS SEQUENCE.
Single membrane vesicles, generally made of PHOSPHOLIPIDS.
An acid dye used in testing for hydrochloric acid in gastric contents. It is also used histologically to test for AMYLOIDOSIS.
A heavy metal trace element with the atomic symbol Cu, atomic number 29, and atomic weight 63.55.
Peptides composed of between two and twelve amino acids.
Pyrrole containing pigments found in photosynthetic bacteria.
A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.
The deductive study of shape, quantity, and dependence. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)
A non-essential amino acid that occurs in high levels in its free state in plasma. It is produced from pyruvate by transamination. It is involved in sugar and acid metabolism, increases IMMUNITY, and provides energy for muscle tissue, BRAIN, and the CENTRAL NERVOUS SYSTEM.
An enzyme that catalyzes the endonucleolytic cleavage to 3'-phosphomononucleotide and 3'-phospholigonucleotide end-products. It can cause hydrolysis of double- or single-stranded DNA or RNA. (From Enzyme Nomenclature, 1992) EC
Artificially produced membranes, such as semipermeable membranes used in artificial kidney dialysis (RENAL DIALYSIS), monomolecular and bimolecular membranes used as models to simulate biological CELL MEMBRANES. These membranes are also used in the process of GUIDED TISSUE REGENERATION.
An essential amino acid. It is often added to animal feed.
Positively charged atoms, radicals or groups of atoms which travel to the cathode or negative pole during electrolysis.
A colorless, odorless, highly water soluble vinyl monomer formed from the hydration of acrylonitrile. It is primarily used in research laboratories for electrophoresis, chromatography, and electron microscopy and in the sewage and wastewater treatment industries.
A chemical system that functions to control the levels of specific ions in solution. When the level of hydrogen ion in solution is controlled the system is called a pH buffer.
Polymers synthesized by living organisms. They play a role in the formation of macromolecular structures and are synthesized via the covalent linkage of biological molecules, especially AMINO ACIDS; NUCLEOTIDES; and CARBOHYDRATES.
A benzimidazole antifilarial agent; it is fluorescent when it binds to certain nucleotides in DNA, thus providing a tool for the study of DNA replication; it also interferes with mitosis.
A basic polypeptide isolated from Streptomyces netropsis. It is cytotoxic and its strong, specific binding to A-T areas of DNA is useful to genetics research.
Proteins conjugated with deoxyribonucleic acids (DNA) or specific DNA.
The process of cleaving a chemical compound by the addition of a molecule of water.
Proteins obtained from species in the class of AMPHIBIANS.

R73A and H144Q mutants of the yeast mitochondrial cyclophilin Cpr3 exhibit a low prolyl isomerase activity in both peptide and protein-folding assays. (1/11120)

Previously we reported that the R73A and H144Q variants of the yeast cyclophilin Cpr3 were virtually inactive in a protease-coupled peptide assay, but retained activity as catalysts of a proline-limited protein folding reaction [Scholz, C. et al. (1997) FEBS Lett. 414, 69-73]. A reinvestigation revealed that in fact these two mutations strongly decrease the prolyl isomerase activity of Cpr3 in both the peptide and the protein-folding assay. The high folding activities found previously originated from a contamination of the recombinant Cpr3 proteins with the Escherichia coli protein SlyD, a prolyl isomerase that co-purifies with His-tagged proteins. SlyD is inactive in the peptide assay, but highly active in the protein-folding assay.  (+info)

Biophysical characterization of the structure of the amino-terminal region of gp41 of HIV-1. Implications on viral fusion mechanism. (2/11120)

A peptide of 51 amino acids corresponding to the NH2-terminal region (5-55) of the glycoprotein gp41 of human immunodeficiency virus type 1 was synthesized to study its conformation and assembly. Nuclear magnetic resonance experiments indicated the sequence NH2-terminal to the leucine zipper-like domain of gp41 was induced into helix in the micellar solution, in agreement with circular dichroism data. Light scattering experiment showed that the peptide molecules self-assembled in water into trimeric structure on average. That the peptide molecules oligomerize in aqueous solution was supported by gel filtration and diffusion coefficient experiments. Molecular dynamics simulation based on the NMR data revealed a flexible region adjacent to the hydrophobic NH2 terminus of gp41. The biological significance of the present findings on the conformational flexibility and the propensity of oligomerization of the peptide may be envisioned by a proposed model for the interaction of gp41 with membranes during fusion process.  (+info)

Reaction specificity of native and nicked 3,4-dihydroxyphenylalanine decarboxylase. (3/11120)

3,4-Dihydroxyphenylalanine (Dopa) decarboxylase is a stereospecific pyridoxal 5'-phosphate (PLP)-dependent alpha-decarboxylase that converts L-aromatic amino acids into their corresponding amines. We now report that reaction of the enzyme with D-5-hydroxytryptophan or D-Dopa results in a time-dependent inactivation and conversion of the PLP coenzyme to pyridoxamine 5'-phosphate and PLP-D-amino acid Pictet-Spengler adducts, which have been identified by high performance liquid chromatography. We also show that the reaction specificity of Dopa decarboxylase toward aromatic amines depends on the experimental conditions. Whereas oxidative deamination occurs under aerobic conditions (Bertoldi, M., Moore, P. S., Maras, B., Dominici, P., and Borri Voltattorni, C. (1996) J. Biol. Chem. 271, 23954-23959; Bertoldi, M., Dominici, P., Moore, P. S., Maras, B., and Borri Voltattorni, C. (1998) Biochemistry 37, 6552-6561), half-transamination and Pictet-Spengler reactions take place under anaerobic conditions. Moreover, we examined the reaction specificity of nicked Dopa decarboxylase, obtained by selective tryptic cleavage of the native enzyme between Lys334 and His335. Although this enzymatic species does not exhibit either decarboxylase or oxidative deamination activities, it retains a large percentage of the native transaminase activity toward D-aromatic amino acids and displays a slow transaminase activity toward aromatic amines. These transamination reactions occur concomitantly with the formation of cyclic coenzyme-substrate adducts. Together with additional data, we thus suggest that native Dopa decarboxylase can exist as an equilibrium among "open," "half-open," and "closed" forms.  (+info)

SNARE interactions are not selective. Implications for membrane fusion specificity. (4/11120)

The SNARE hypothesis proposes that membrane trafficking specificity is mediated by preferential high affinity interactions between particular v (vesicle membrane)- and t (target membrane)-SNARE combinations. The specificity of interactions among a diverse set of SNAREs, however, is unknown. We have tested the SNARE hypothesis by analyzing potential SNARE complexes between five proteins of the vesicle-associated membrane protein (VAMP) family, three members of the synaptosome-associated protein-25 (SNAP-25) family and three members of the syntaxin family. All of the 21 combinations of SNAREs tested formed stable complexes. Sixteen were resistant to SDS denaturation, and most complexes thermally denatured between 70 and 90 degreesC. These results suggest that the specificity of membrane fusion is not encoded by the interactions between SNAREs.  (+info)

The putative bioactive surface of insect-selective scorpion excitatory neurotoxins. (5/11120)

Scorpion neurotoxins of the excitatory group show total specificity for insects and serve as invaluable probes for insect sodium channels. However, despite their significance and potential for application in insect-pest control, the structural basis for their bioactivity is still unknown. We isolated, characterized, and expressed an atypically long excitatory toxin, Bj-xtrIT, whose bioactive features resembled those of classical excitatory toxins, despite only 49% sequence identity. With the objective of clarifying the toxic site of this unique pharmacological group, Bj-xtrIT was employed in a genetic approach using point mutagenesis and biological and structural assays of the mutant products. A primary target for modification was the structurally unique C-terminal region. Sequential deletions of C-terminal residues suggested an inevitable significance of Ile73 and Ile74 for toxicity. Based on the bioactive role of the C-terminal region and a comparison of Bj-xtrIT with a Bj-xtrIT-based model of a classical excitatory toxin, AaHIT, a conserved surface comprising the C terminus is suggested to form the site of recognition with the sodium channel receptor.  (+info)

Properties of non-polymerizable tropomyosin obtained by carboxypeptidase A digestion. (6/11120)

Tropomyosin digested with carboxypeptidase A [EC] (CTM) shows a lower viscosity than the undigested protein in solution. From the relation between the viscosity decrease and the amount of amino acids liberated from the carboxyl terminus during this digestion, it is inferred that loss of the tri-peptide-Thr-Ser-Ile from the C-terminus is responsible for the decrease in viscosity. The secondary structure of -TM was not affected by the digestion according to circular dichroic measurements. The viscosity of CTM did not increase in methanol-water mixtures, whereas that of tropomyosin increased markedly. These results indicate that polymerizability was lost upon the removal of a small peptide from the C-terminus without change in the secondary structure. A decrease in the viscosity of tropomyosin solutions was observed on the addition of CTM, indicating that CTM interacts with intact tropomyosin. The dependence of the viscosity decrease on the amount of CTM showed that CTM binds tropomyosin in a one-to-one ratio as a result of end-to-end interaction. Since paracrystals having a 400 A repeated band structure could be grown in the presence of Mg ions at neutral pH, side-by-side interactions in CTM molecules remain intact, even though polymerizability is lost. The disc gel electrophoretic pattern showed that troponin could bind to CTM, but no increase in viscosity due to the complex was observed in solution. That is, the C-terminal part of tropomyosin is not required for the formation of the complex. The amount of CTM bound to F-actin was less than half of that bound to undigested tropomyosin, and could be reduced to one-tenth by a washing procedure. In the presence of troponin, however, the amount recovered to the level of tropomyosin normally bound to F-actin. Therefore, it is concluded that troponin is bound in the middle of the tropomyosin molecule and strengthens the binding of tropomyosin to F-actin.  (+info)

Characterisation of copper-binding to the second sub-domain of the Menkes protein ATPase (MNKr2). (7/11120)

The Menkes ATPase (MNK) has an essential role in the translocation of copper across cellular membranes. In a complementary manner, the intracellular concentration of copper regulates the activity and cellular location of the ATPase through its six homologous amino-terminal domains. The roles of the six amino-terminal domains in the activation and cellular trafficking processes are unknown. Understanding the role of these domains relies on the development of an understanding of their metal-binding properties and structural properties. The second conserved sub-domain of MNK was over-expressed, purified and its copper-binding properties characterised. Reconstitution studies demonstrate that copper binds to MNKr2 as Cu(I) with a stoichiometry of one copper per domain. This is the first direct evidence of copper-binding to the MNK amino-terminal repeats. Circular dichroism studies suggest that the binding or loss of copper to MNKr2 does not cause substantial changes to the secondary structure of the protein.  (+info)

Biophysical characterization of a designed TMV coat protein mutant, R46G, that elicits a moderate hypersensitivity response in Nicotiana sylvestris. (8/11120)

The hypersensitivity resistance response directed by the N' gene in Nicotiana sylvestris is elicited by the tobacco mosaic virus (TMV) coat protein R46G, but not by the U1 wild-type TMV coat protein. In this study, the structural and hydrodynamic properties of R46G and wild-type coat proteins were compared for variations that may explain N' gene elicitation. Circular dichroism spectroscopy reveals no significant secondary or tertiary structural differences between the elicitor and nonelicitor coat proteins. Analytical ultracentrifugation studies, however, do show different concentration dependencies of the weight average sedimentation coefficients at 4 degrees C. Viral reconstitution kinetics at 20 degrees C were used to determine viral assembly rates and as an initial assay of the rate of 20S formation, the obligate species for viral reconstitution. These kinetic results reveal a decreased lag time for reconstitution performed with R46G that initially lack the 20S aggregate. However, experiments performed with 20S initially present reveal no detectable differences indicating that the mechanism of viral assembly is similar for the two coat protein species. Therefore, an increased rate of 20S formation from R46G subunits may explain the differences in the viral reconstitution lag times. The inferred increase in the rate of 20S formation is verified by direct measurement of the 20S boundary as a function of time at 20 degrees C using velocity sedimentation analysis. These results are consistent with the interpretation that there may be an altered size distribution and/or lifetime of the small coat protein aggregates in elicitors that allows N. sylvestris to recognize the invading virus.  (+info)

Research Corridor has published a new research study titled Circular Dichroism Spectroscopy Market - Growth, Share, Opportunities, Competitive Analysis and Forecast, 2017 - 2025. The Circular Dichroism Spectroscopy Market report studies current as well as future aspects of the Circular Dichroism Spectroscopy Market based upon factors such as market dynamics, key ongoing trends and segmentation analysis. Apart from the above elements, the Circular Dichroism Spectroscopy Market research report provides a 360-degree view of the Lipstick Packing industry with geographic segmentation, statistical forecast and the competitive landscape.. Browse the complete report at http://www.researchcorridor.com/circular-dichroism-spectroscopy-market/. Geographically, the Circular Dichroism Spectroscopy Market report comprises dedicated sections centering on the regional market revenue and trends. The Circular Dichroism Spectroscopy Market has been segmented on the basis of geographic regions into North America, ...
The relative configuration of a key subunit of hemicalide, a recently isolated, highly bioactive marine natural product having potent antiproliferative activity against a panel of human cancer cell lines, was assigned by combining stereocontrolled synthesis of model substrates with NMR, IR, and vibrational circular dichroism (VCD) spectroscopy. The assignment of the absolute configuration of asymmetric carbon center C42 in two structurally complex epimeric substructures containing six stereocenters by VCD analysis illustrates the power and reliability of combining methods. ...
Circular Dichroism and Magnetic Circular Dichroism Spectroscopy for Organic Chem... Circular Dichroism and Magnetic Circular Dichroism Spectroscopy for Organic Chem... ...
Nicu, V. and Neugebauer, J. and Wolff, S. and Baerends, E. 2008. A vibrational circular dichroism implementation within a Slater-type-orbital based density functional framework and its application to hexa- and hepta-helicenes. Theoretical Chemistry Accounts: Theory, Computation, and Modeling (Theoretica Chimica Acta). 119: pp. 245-263 ...
2017-2022 Southeast Asia and Regional Vibrational Circular Dichroism Spectrometer Industry Production, Sales and Consumption Status and Prospects Professional Market Research Report
Circular dichroism measurements of ArsTM (purple) and MamAΔ41 proteins from RS-1 (Blue) Mbav (orange), AMB-1 (green) and MSR-1 (red).(A) Circular dichroism spe
Bertucci C., Cimitan S., Riva A., Morazzoni P.. The binding to human serum albumin (HSA) of the antitumoural drug paclitaxel and of several structural analogues has been characterized by bioaffinity chromatography and circular dichroism. A ranking of the taxanes was obtained for their affinity to the protein by measuring their retention times on an albumin chromatographic column. This also allowed the calculation of the drug bound percentage. Affinity resulted significantly affected by the nature of the isoserinic side chain, the presence of the 1,14-carbonate moiety and the substituent at C-7, showing that the hydrophobicity of the drug is fundamental in the binding process. The analysis demonstrated that the organic solvent highly alters the interaction mechanism of taxanes to the protein and so the affinity results. Circular dichroism experiments supported this hypothesis. Furthermore, taxanes binding to the serum carrier was characterized by displacement chromatography, by adding into the ...
TY - JOUR. T1 - Measurement of circular dichroism of ferroelectric fresnoite Ba 2Si2TiO8. AU - Asahi, Toni. AU - Osaka, Tetsuya. AU - Abrahamsb, Sidney C.. AU - Matsuki, Ryo. AU - Asai, Hiroshi. AU - Nanamatsu, Satoshi. AU - Kobayashi, Jinzo. PY - 2003/12/1. Y1 - 2003/12/1. N2 - The urgent goal of the optical polarimetry of solids is simultaneous and accurate measurements of circular dichroism together with circular birefringence. Needless to say, measurements of circular phenomena are extremely difficult compared with those of linear ones. As for circular birefringence, 170 years elapsed since its discovery by Arago until the development of the HAUP method, by which the accurate measurements of the gyration tensor components of a solid became possible for the first time. Subsequent to appearance of the HAUP method, attempts to extend the HAUP theory to being applicable for measurements of circular dichroism of crystals were followed by several authors. However any applications to real crystal ...
TY - JOUR. T1 - Tunable circular dichroism and valley polarization in the modified Haldane model. AU - Vila, Marc. AU - Hung, Nguyen Tuan. AU - Roche, Stephan. AU - Saito, Riichiro. PY - 2019/4/16. Y1 - 2019/4/16. N2 - © 2019 American Physical Society. We study the polarization dependence of optical absorption for a modified Haldane model, which exhibits antichiral edge modes in the presence of sample boundaries and has been argued to be realizable in transition metal dichalcogenides or Weyl semimetals. A rich optical phase diagram is unveiled, in which the correlations between perfect circular dichroism, pseudospin andvalley polarization can be tuned independently upon varying the Fermi energy. In particular, perfect circular dichroism and valley polarization are achieved simultaneously. This combination of optical properties suggests some interesting photonic device functionality (e.g., light polarizer) which could be combined with valleytronics applications (e.g., generation of valley ...
The preparations of pentaamminecobalt(III) complexes of a series of asymmetric unidentate amines are reported. The circular dichroism spectra for the (S)-amines show negative Cotton effects under the A → T absorption band, which are somewhat solvent dependent but independent of temperature down to -190°C. The vicinal effect from 1-cyclohexylethylamine was comparable to that from analogous aromatic compounds, but the simpler alkyl derivatives were found to impose smaller rotational strengths on the d-d transitions. The lack of measurable c.d. in the visible region for tetraammine((S)-butane-1, 3-diamine)cobalt(III) is reported and discussed in the light of the other studies ...
Read Secondary Structure of Proteins Through Circular Dichroism Spectroscopy, Annual Review of Biophysics on DeepDyve, the largest online rental service for scholarly research with thousands of academic publications available at your fingertips.
Philip J. Stephens was a theoretical chemist who brought to fruition two new forms of optical spectroscopy, using circularly polarized light, for the determination of electronic structure and molecular stereochemistry. The first was magnetic circular dichroism (MCD), the wavelength dependence of the differential absorption of left and right circularly polarized light induced by a magnetic field applied parallel to the light beam. Stephens established a methodology for extracting from MCD spectra the angular momentum characteristics of ground and excited electronic states and demonstrated applications to the assignment of the optical spectra of coordination complexes of transition metals and to metalloproteins. In the second half of his career Stephens led the field of vibrational circular dichroism (VCD), the measurement of the natural circular dichroism (CD) arising from the vibrational transitions of chiral molecules. He developed instrumental techniques to measure this weak dichroism over a ...
Circular Dichroism (CD) analysis from SGS - meet regulatory requirements with class-leading CD spectroscopic analysis, alpha helix beta sheet analysis, and secondary and tertiary structure analysis. Learn more.
The circular-dichroism and proton-magnetic-resonance spectra of complexes of ribonuclease A with dihydrouridine 3′-phosphate, 2′- and 3′-CMP, arabinosyl-3′-CMP, 1-(2-hydroxyethyl)cytosine 2′-phosphate and 1-(3-hydroxypropyl)cytosine 3′-phosphate were studied. Comparison of the results shows that non-additivity of the circular-dichroic spectrum of an enzyme-nucleotide complex may be due to: (a), alteration of the circular dichroic spectrum of the nucleotide under the influence of the asymmetric protein matrix (induced dichroism), and (b) a change in the nucleotide conformation. The contribution of each of the two factors was estimated to calculate the circular-dichoroic spectra of 2′-CMP and 3′-CMP in complex with ribonuclease A. 3′-CMP in this complex was characterized by negative circular dichroism in the long-wavelength absorption band of the nucleotide, whereas 2′-CMP was characterized by positive circular dichroism. Since both nucleotides in the complex are known to be in ...
The circular-dichroism and proton-magnetic-resonance spectra of complexes of ribonuclease A with dihydrouridine 3′-phosphate, 2′- and 3′-CMP, arabinosyl-3′-CMP, 1-(2-hydroxyethyl)cytosine 2′-phosphate and 1-(3-hydroxypropyl)cytosine 3′-phosphate were studied. Comparison of the results shows that non-additivity of the circular-dichroic spectrum of an enzyme-nucleotide complex may be due to: (a), alteration of the circular dichroic spectrum of the nucleotide under the influence of the asymmetric protein matrix (induced dichroism), and (b) a change in the nucleotide conformation. The contribution of each of the two factors was estimated to calculate the circular-dichoroic spectra of 2′-CMP and 3′-CMP in complex with ribonuclease A. 3′-CMP in this complex was characterized by negative circular dichroism in the long-wavelength absorption band of the nucleotide, whereas 2′-CMP was characterized by positive circular dichroism. Since both nucleotides in the complex are known to be in ...
Circular dichroism (CD) spectroscopy is an optical technique that measures the difference in the absorption of left and right circularly polarized light. This technique has been widely employed in the studies of nucleic acids structures and the use of it to monitor conformational polymorphism of DNA has grown tremendously in the past few decades. DNA may undergo conformational changes to B-form, A-form, Z-form, quadruplexes, triplexes and other structures as a result of the binding process to different compounds. Here we review the recent CD spectroscopic studies of the induction of DNA conformational changes by different ligands, which includes metal derivative complex of aureolic family drugs, actinomycin D, neomycin, cisplatin, and polyamine. It is clear that CD spectroscopy is extremely sensitive and relatively inexpensive, as compared with other techniques. These studies show that CD spectroscopy is a powerful technique to monitor DNA conformational changes resulting from drug binding and also
A new method to detect the vibrational CD (VCD) of a localized part of a chiral mol. system is reported. A local VCD amplifier was implemented, and the distance dependence of the amplification was investigated in a series of peptides. The results indicate a characteristic distance of 2.0±0.3 bonds, which suggests that the amplification is a localized phenomenon. The amplifier can be covalently coupled to a specific part of a mol., and can be switched ON and OFF electrochem. By subtracting the VCD spectra obtained when the amplifier is in the ON and OFF states, the VCD of the local environment of the amplifier can be sepd. from the total VCD spectrum. Switchable local VCD amplification thus makes it possible to zoom in on a specific part of a chiral mol ...
A series of polypeptides with well-defined sequences, (Asp3Phe1)n, (Asp2Phe1)n, (Asp1Phe1)n, (Asp1Phe2)n, and (Asp1Phe3)n, containing the hydrophilic amino acid, aspartic acid (Asp) and the hydrophobic amino acid, phenylalanine (Phe), were synthesized. Their behaviour in aqueous solution was investigated by performing fluorescence quenching and non-radiative energy transfer (NRET) experiments which were complemented by dynamic (DLS) and static (SLS) light scattering. The photophysical properties of the polypeptides were dependent on their Phe content. An increase in the Phe content led to an increase in the extinction coefficient, fluorescence quantum yield, and fluorescence average lifetime of the polypeptides. Circular dichroism experiments revealed that except for the (Asp1Phe3)n polypeptide, which adopts an alpha-helical conformation in aqueous solution, the other polypeptides did not adopt any known conformation in solution. The fluorescence quenching studies performed using molecular ...
Circular dichroism (CD) is a powerful technique for studying the structures of proteins in solution, as well as structural changes that may occur when proteins bind to ligands
The Aviv Circular Dichroism Spectrometer, model 215, records CD as a function of wavelength, time, temperature, pH and concentration using a double monochromator containing two UV grade prisms as dispersing elements. Right and left circularly polarized light is produced by a 50 KHz photoelastic modulator.. The instrument includes software by AVIV for instrument control, data acquisition and processing in a Windows environment.. ...
Introducing one or two alkynyl-iron moieties onto a carbo[6]helicene results in organometallic helicenes (2 a,b) that display strong chiroptical activity combined with efficient redox-triggered switching. The neutral and oxidized forms have been studied in detail by electronic and vibrational circular dichroism, as well as by Raman optical activity (ROA) spectroscopy. The experimental results were analyzed and spectra were assigned with the help of first-principles calculations. In particular, a recently developed method for ROA calculations under resonance conditions has been used to study the intricate resonance effects on the ROA spectrum of mono-iron ethynylhelicene 2 a.
Ferromagnetic amorphous oxides in the EuO-TiO[2] system studied by the Faraday effect in the visible region and the x-ray magnetic circular dichroism at the Eu M[4,5] and L[2,3] edges (2013 ...
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Herein we describe a straightforward method for the determination of the absolute con?guration of 3-indolyl(bromo)acetate 7, 3-indolyl(alkoxy)acetates 8a?f and 3-indolyl(amino)acetate 8g, based on 1HNMR spectral analysis. The conformational preferences for two diastereomeric esters were calculatedby DFT, which matched very well with the experimental results. X-ray diffraction analysis allowed usto validate the methodology, and independent absolute con?guration evidence was obtained by vibrational circular dichroism. ...
The focus of my PhD has been the development of new instrumentation for UV polarised spectroscopic methods, especially that of circular dichroism (CD). Whilst instrument design is an unusual field of research (especially for a chemist!) I feel it is one of great importance to the scientific process. The instruments that scientists employ to study the world around us are our eyes and ears, enabling us to view objects from the angstrom level to distant galaxies. In many ways, it could be argued that the limiting factor for the majority of research is the methods that we can employ. By improving these methods, we naturally enhance the quality of our research and further understanding. Capillary circular dichroism (CaCD). One of the key problems with circular dichroism as a technique is its relatively high sample requirments for each reading. In order to address this problem, we have been working on using extruded quartz capillaries as an inexpensive alternative sample holder to the rectangular ...
The extension of circular dichroism measurements into the VUV region was motivated by the need to provide supplementary techniques to the absorption studies lacking rotational and vibrational structure. CD as one of these techniques is determined by selection rules which differ from those in absorption and thus enables the assignment of excited electronic states. Another application of VUVCD measurements is the use of correlation between the sign of the CD signal and the absolute configuration to formulate sector rules of chromophores absorbing only in the VUV. In this review we will present results obtained on our home-made instrument capable of measuring CD signal down to 150 nm. These applications of VUVCD will be demonstrated in systems such as the oxirane chromophore, the methylenecyclohexene chromophore and the amine chromophore. The role of singlet-triplet transitions and their contribution to CD and ORD will also be discussed. ...
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This Jasco J-815 CD System comes loaded with accessories including a 6-sample Peltier Turret Cell Changer (Model MPTC-490S/15), a Julabo Circulating Water Bath
We are a biophysical chemistry group that is focused on understanding the mechanism of entry by viruses enveloped by a membrane. Many important human pathogens are enveloped viruses, including Human Immunodeficiency (HIV), Influenza, Measles, Rabies, West Nile, Zika, Ebola, SARS, and MERS. Each virus has evolved a protein in its membrane that catalyzes the joining (fusion) of the virus membrane with the membrane of the target cell. We are studying the glycoprotein 41 kDa (gp41) fusion protein of HIV and hemagglutinin subunit 2 (HA2) fusion protein of influenza. Our work and contributions include the protein structures and locations in membrane. We also study the changes in membrane structure associated with the protein. A significant fraction of our effort is in development and application of solid-state, i.e. anisotropic nuclear magnetic resonance (NMR) to these proteins. We also apply a variety of other biophysical methods including circular dichroism spectroscopy, fluorescence ...
Phase-modulated ellipsometry of the J-aggregates of the title porphyrin shows that the material gives a true CD signal. This confirms that there is a real chiral transfer by mechanical forces, mediated by shear gradient flows, from the macroscopic to the electronic transition level. Dislocations in the structure of the aggregate could justify the formation of chirality at the level of the electronic transitions once the mesophases can be sculptured by hydrodynamic gradient flows ...
In this report, we provide an x-ray magnetic circular dichroism (XMCD) study for 100?nm thick epitaxial magnetite (Fe3O4) films on MgO (001) and Al2O3 (0001) substrates. For XMCD, we recorded the surface sensitive total electron yield and the bulk sensitive transmission spectra. From the analysis of the XMCD data, we find an increased Fe spin moment (10% larger) at the surface of the film on MgO (100) with respect to the corresponding bulk value of the film. Surface and bulk spin moments of the film on Al2O3(0001) are almost equal. For both films, the bulk orbital to spin moments ratio increases from zero at 70?K to 0.03?0.04 at 300?K. For Fe3O4/MgO (001), the surface orbital to spin moment ratio behaves similarly to the bulk value, while the orbital to spin moments ratio is increased at the Fe3O4/Al2O3 (0001) surface to 0.06. The observed differences between films grown on MgO and Al2O3 are explained within the framework of differences in mismatch strain experienced by the films. ...
On the basis of temperature-dependent UV-vis and circular dichroism (CD) spectroscopy measurements, we observed that C3-symmetrical discotic molecules, chiral (R)-1 and achiral 2, both self-assemble in a highly cooperative fashion. Chiral (R)-1 shows a higher degree of cooperativity, meaning it requ …
Biophotonics. Bioelectromagnetics. Calcium imaging. Calorimetry. Chromatography. Circular dichroism. Computational chemistry. Cryobiology. Dual-polarization. .
The CD spectra of d(GGGGTTTTGGGG) and d(TGGGGTTGGGGT) in the presence of 5 and 140 mM sodium are shown in the upper panels. The CD spectra of these DNAs in the
Circular Dichroism, DNA, Absorption, Nickel, Z-dna, B-dna, Report, Spermine, Cadmium, Concentrations, Cytosine, Guanine, Fluorescence, Ionic Strength, Oligonucleotides, Adenine, Electronic, Light, Porphyrins, Sensitivity
Kinase, Lipids, Membrane, Liposomes, Membranes, Micelles, Rapamycin, Association, Circular Dichroism, Concentrations, Environment, Fkbp12, Growth, Magnetic, Magnetic Resonance, Membrane Protein, Metabolism, Neurological Disorders, Nuclear Magnetic Resonance, Phosphatidic Acid
The Dark Animus 10hc topic was quite useful so I figured perhaps people have some advice for lei shen 10hc. Currently getting to the second transition, getting past the first transition without casualties is our current main issue so we waste alot of attempts on that. Any input overall is welcome tho.
hai, i am transmitting cd data from client to server and transmission is done. then i added some control transmission,if server sends 1, client
The purpose of Circular 2010/4 is to provide APS agencies with updated information originally published in Circular 2006/1 about the: Special Measures provision for recruiting Indigenous staff; and Identified Positions/Criteria provision for recruiting staff with specialist knowledge and understanding for roles with a strong involvement in work relating to Indigenous
Ngày 25/02/2014,Bộ Nông nghiệp và Phát triển nông thôn đã ban hành Circular No. 08/VBHN-BNNPTNT 2014 list of banned restricted drugs chemicals antibiotics Thuộc lĩnh vực Thể thao - Y tế và sẽ có hiệu lực kể từ ngày 25/02/2014
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This example covers four tests that are available in the StatsCircularTwoSampleTest operation. All tests are used to compare two samples of circular data which represent either raw data or means of data (second order analysis).. For the first two examples we use the waves Sample1, Sample2 and Sample3:. ...
Hi everyone, I create a blank solution, then create two class projects in it. Its a requirement that i must create a reference from each project to the other. But VS doesnt allow me to do it. It...
Bayesian length-weight: a=0.01000 (0.00244 - 0.04107), b=3.04 (2.81 - 3.27), in cm Total Length, based on all LWR estimates for this body shape (Ref. 93245 ...
push complete. go ahead and test it out :) Updating code... Updating vendor submodules... syncdb migrate manage.py tasks... Cleaning gitignore and pyc files... Storing revision information... finished at Mon Apr 30 14:13:33 PDT 2012 Deploying code... [2012-04-30 14:13:33] Running rsync_project [2012-04-30 14:13:33] [localhost] running: /usr/bin/rsync -aq --include .gitkeep --exclude .git* --exclude .hg* --delete /data/genericrhel6-stage/src/mozillalabs.allizom.org/ /data/genericrhel6-stage/www/mozillalabs.allizom.org/ [2012-04-30 14:13:35] [localhost] finished: /usr/bin/rsync -aq --include .gitkeep --exclude .git* --exclude .hg* --delete /data/genericrhel6-stage/src/mozillalabs.allizom.org/ /data/genericrhel6-stage/www/mozillalabs.allizom.org/ (2.497s) [2012-04-30 14:13:35] Running commit_www [2012-04-30 14:13:35] [localhost] running: cd /data/genericrhel6-stage/www && /usr/bin/git add .; /usr/bin/git commit -a -m deploy [2012-04-30 14:14:09] [localhost] finished: cd ...

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