Sulfonic Acids: Inorganic or organic oxy acids of sulfur which contain the RSO2(OH) radical.Trinitrobenzenesulfonic Acid: A reagent that is used to neutralize peptide terminal amino groups.Naphthalenesulfonates: A class of organic compounds that contains a naphthalene moiety linked to a sulfonic acid salt or ester.Anilino Naphthalenesulfonates: 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.Colitis: Inflammation of the COLON section of the large intestine (INTESTINE, LARGE), usually with symptoms such as DIARRHEA (often with blood and mucus), ABDOMINAL PAIN, and FEVER.Alkanesulfonic Acids: Sulfonic acid derivatives that are substituted with an aliphatic hydrocarbon group.Benzothiazoles: Compounds with a benzene ring fused to a thiazole ring.Sulfanilic Acids: Aminobenzenesulfonic acids. Organic acids that are used in the manufacture of dyes and organic chemicals and as reagents.Unithiol: A chelating agent used as an antidote to heavy metal poisoning.Colon: The segment of LARGE INTESTINE between the CECUM and the RECTUM. It includes the ASCENDING COLON; the TRANSVERSE COLON; the DESCENDING COLON; and the SIGMOID COLON.Alkanesulfonates: Organic esters or salts of sulfonic acid derivatives containing an aliphatic hydrocarbon radical.Laccase: A copper-containing oxidoreductase enzyme that catalyzes the oxidation of 4-benzenediol to 4-benzosemiquinone. It also has activity towards a variety of O-quinols and P-quinols. It primarily found in FUNGI and is involved in LIGNIN degradation, pigment biosynthesis and detoxification of lignin-derived products.PicratesSaussurea: A plant genus of the family ASTERACEAE, order Asterales, subclass Asteridae. It is a source of costus root oil and should not be confused with the genus COSTUS.Dinitrofluorobenzene: Irritants and reagents for labeling terminal amino acid groups.Spectrometry, Fluorescence: Measurement of the intensity and quality of fluorescence.Peroxidase: A hemeprotein from leukocytes. Deficiency of this enzyme leads to a hereditary disorder coupled with disseminated moniliasis. It catalyzes the conversion of a donor and peroxide to an oxidized donor and water. EC Carmine: Indolesulfonic acid used as a dye in renal function testing for the detection of nitrates and chlorates, and in the testing of milk.Fluorescent Dyes: Agents that emit light after excitation by light. The wave length of the emitted light is usually longer than that of the incident light. Fluorochromes are substances that cause fluorescence in other substances, i.e., dyes used to mark or label other compounds with fluorescent tags.Sulfenic Acids: Oxy acids of sulfur with the general formula RSOH, where R is an alkyl or aryl group such as CH3. They are often encountered as esters and halides. (From McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Isatin: An indole-dione that is obtained by oxidation of indigo blue. It is a MONOAMINE OXIDASE INHIBITOR and high levels have been found in urine of PARKINSONISM patients.Petasites: A plant genus of the family ASTERACEAE. Members contain SESQUITERPENES. The common name of sweet coltsfoot is similar to the common name for TUSSILAGO.Cysteine: A thiol-containing non-essential amino acid that is oxidized to form CYSTINE.Sulfhydryl Reagents: Chemical agents that react with SH groups. This is a chemically diverse group that is used for a variety of purposes. Among these are enzyme inhibition, enzyme reactivation or protection, and labelling.Administration, Rectal: The insertion of drugs into the rectum, usually for confused or incompetent patients, like children, infants, and the very old or comatose.Camphor: A bicyclic monoterpene ketone found widely in plants, especially CINNAMOMUM CAMPHORA. It is used topically as a skin antipruritic and as an anti-infective agent.Benzenesulfonates: Organic salts and esters of benzenesulfonic acid.Fluorocarbons: Liquid perfluorinated carbon compounds which may or may not contain a hetero atom such as nitrogen, oxygen or sulfur, but do not contain another halogen or hydrogen atom. This concept includes fluorocarbon emulsions and fluorocarbon blood substitutes.Cysteic Acid: Beta-Sulfoalanine. An amino acid with a C-terminal sulfonic acid group which has been isolated from human hair oxidized with permanganate. It occurs normally in the outer part of the sheep's fleece, where the wool is exposed to light and weather.Intestinal Mucosa: Lining of the INTESTINES, consisting of an inner EPITHELIUM, a middle LAMINA PROPRIA, and an outer MUSCULARIS MUCOSAE. In the SMALL INTESTINE, the mucosa is characterized by a series of folds and abundance of absorptive cells (ENTEROCYTES) with MICROVILLI.Sulfur Isotopes: Stable sulfur atoms that have the same atomic number as the element sulfur, but differ in atomic weight. S-33, 34, and 36 are stable sulfur isotopes.Cytophaga: A genus of gram-negative gliding bacteria found in SOIL; HUMUS; and FRESHWATER and marine habitats.Sesquiterpenes, Eudesmane: SESQUITERPENES cyclized into two adjoining cyclohexane rings but with a different configuration from the ARTEMISININS.Inflammatory Bowel Diseases: Chronic, non-specific inflammation of the GASTROINTESTINAL TRACT. Etiology may be genetic or environmental. This term includes CROHN DISEASE and ULCERATIVE COLITIS.Free Radical Scavengers: Substances that influence the course of a chemical reaction by ready combination with free radicals. Among other effects, this combining activity protects pancreatic islets against damage by cytokines and prevents myocardial and pulmonary perfusion injuries.Dextran Sulfate: Long-chain polymer of glucose containing 17-20% sulfur. It has been used as an anticoagulant and also has been shown to inhibit the binding of HIV-1 to CD4-POSITIVE T-LYMPHOCYTES. It is commonly used as both an experimental and clinical laboratory reagent and has been investigated for use as an antiviral agent, in the treatment of hypolipidemia, and for the prevention of free radical damage, among other applications.Oxyquinoline: An antiseptic with mild fungistatic, bacteriostatic, anthelmintic, and amebicidal action. It is also used as a reagent and metal chelator, as a carrier for radio-indium for diagnostic purposes, and its halogenated derivatives are used in addition as topical anti-infective agents and oral antiamebics.Kinetics: The rate dynamics in chemical or physical systems.Hydrogen-Ion Concentration: 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)Protein Denaturation: Disruption of the non-covalent bonds and/or disulfide bonds responsible for maintaining the three-dimensional shape and activity of the native protein.Oxidation-Reduction: 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).Circular Dichroism: 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)Biphenyl CompoundsDisease Models, Animal: Naturally occurring or experimentally induced animal diseases with pathological processes sufficiently similar to those of human diseases. They are used as study models for human diseases.Protein Conformation: 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).Visceral Afferents: The sensory fibers innervating the viscera.Haptens: Small antigenic determinants capable of eliciting an immune response only when coupled to a carrier. Haptens bind to antibodies but by themselves cannot elicit an antibody response.Energy Transfer: 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.Molecular Structure: 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.Plant Extracts: Concentrated pharmaceutical preparations of plants obtained by removing active constituents with a suitable solvent, which is evaporated away, and adjusting the residue to a prescribed standard.Protein Folding: Processes involved in the formation of TERTIARY PROTEIN STRUCTURE.Caprylates: Derivatives of caprylic acid. Included under this heading are a broad variety of acid forms, salts, esters, and amides that contain a carboxy terminated eight carbon aliphatic structure.Guanidine: 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.Rats, Sprague-Dawley: A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.Binding Sites: The parts of a macromolecule that directly participate in its specific combination with another molecule.Antioxidants: Naturally occurring or synthetic substances that inhibit or retard the oxidation of a substance to which it is added. They counteract the harmful and damaging effects of oxidation in animal tissues.PeroxidasesIndicators and Reagents: Substances used for the detection, identification, analysis, etc. of chemical, biological, or pathologic processes or conditions. Indicators are substances that change in physical appearance, e.g., color, at or approaching the endpoint of a chemical titration, e.g., on the passage between acidity and alkalinity. Reagents are substances used for the detection or determination of another substance by chemical or microscopical means, especially analysis. Types of reagents are precipitants, solvents, oxidizers, reducers, fluxes, and colorimetric reagents. (From Grant & Hackh's Chemical Dictionary, 5th ed, p301, p499)Oxygen Isotopes: Stable oxygen atoms that have the same atomic number as the element oxygen, but differ in atomic weight. O-17 and 18 are stable oxygen isotopes.MercaptoethanolIodoacetamide: An alkylating sulfhydryl reagent. Its actions are similar to those of iodoacetate.Sulfhydryl Compounds: Compounds containing the -SH radical.Taurine: A conditionally essential nutrient, important during mammalian development. It is present in milk but is isolated mostly from ox bile and strongly conjugates bile acids.Mercury: A silver metallic element that exists as a liquid at room temperature. It has the atomic symbol Hg (from hydrargyrum, liquid silver), atomic number 80, and atomic weight 200.59. Mercury is used in many industrial applications and its salts have been employed therapeutically as purgatives, antisyphilitics, disinfectants, and astringents. It can be absorbed through the skin and mucous membranes which leads to MERCURY POISONING. Because of its toxicity, the clinical use of mercury and mercurials is diminishing.Mass Spectrometry: An analytical method used in determining the identity of a chemical based on its mass using mass analyzers/mass spectrometers.Fluorescence Polarization: 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.Suramin: A polyanionic compound with an unknown mechanism of action. It is used parenterally in the treatment of African trypanosomiasis and it has been used clinically with diethylcarbamazine to kill the adult Onchocerca. (From AMA Drug Evaluations Annual, 1992, p1643) It has also been shown to have potent antineoplastic properties.Troponin C: One of the three polypeptide chains that make up the TROPONIN complex of skeletal muscle. It is a calcium-binding protein.Temperature: 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.Phenols: Benzene derivatives that include one or more hydroxyl groups attached to the ring structure.Catalysis: The facilitation of a chemical reaction by material (catalyst) that is not consumed by the reaction.Protein Binding: 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.Mice, Inbred BALB CTryptophan: 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.Hydrogen Peroxide: A strong oxidizing agent used in aqueous solution as a ripening agent, bleach, and topical anti-infective. It is relatively unstable and solutions deteriorate over time unless stabilized by the addition of acetanilide or similar organic materials.Colitis, Ulcerative: Inflammation of the COLON that is predominantly confined to the MUCOSA. Its major symptoms include DIARRHEA, rectal BLEEDING, the passage of MUCUS, and ABDOMINAL PAIN.Oxidoreductases: 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)Cattle: 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.Polymers: Compounds formed by the joining of smaller, usually repeating, units linked by covalent bonds. These compounds often form large macromolecules (e.g., BIOPOLYMERS; PLASTICS).Urea: 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.Basidiomycota: A phylum of fungi that produce their sexual spores (basidiospores) on the outside of the basidium. It includes forms commonly known as mushrooms, boletes, puffballs, earthstars, stinkhorns, bird's-nest fungi, jelly fungi, bracket or shelf fungi, and rust and smut fungi.Fluorescence: 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.Amino Acid Sequence: 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.Rabbits: The species Oryctolagus cuniculus, in the family Leporidae, order LAGOMORPHA. Rabbits are born in burrows, furless, and with eyes and ears closed. In contrast with HARES, rabbits have 22 chromosome pairs.Rats, Wistar: A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.Recombinant Proteins: Proteins prepared by recombinant DNA technology.Protein Structure, Secondary: 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.Structure-Activity Relationship: 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.Chromatography, High Pressure Liquid: Liquid chromatographic techniques which feature high inlet pressures, high sensitivity, and high speed.Free Radicals: Highly reactive molecules with an unsatisfied electron valence pair. Free radicals are produced in both normal and pathological processes. They are proven or suspected agents of tissue damage in a wide variety of circumstances including radiation, damage from environment chemicals, and aging. Natural and pharmacological prevention of free radical damage is being actively investigated.Escherichia coli: 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.Dithiothreitol: A reagent commonly used in biochemical studies as a protective agent to prevent the oxidation of SH (thiol) groups and for reducing disulphides to dithiols.Time Factors: Elements of limited time intervals, contributing to particular results or situations.Anti-Inflammatory Agents: Substances that reduce or suppress INFLAMMATION.Spectrophotometry, Ultraviolet: 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)Enzyme Stability: 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.Molecular Sequence Data: 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.Dose-Response Relationship, Drug: The relationship between the dose of an administered drug and the response of the organism to the drug.Spectrophotometry: The art or process of comparing photometrically the relative intensities of the light in different parts of the spectrum.Magnetic Resonance Spectroscopy: 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).Mice, Inbred C57BLModels, Molecular: Models used experimentally or theoretically to study molecular shape, electronic properties, or interactions; includes analogous molecules, computer-generated graphics, and mechanical structures.Polyporales: An order of fungi in the phylum BASIDIOMYCOTA having macroscopic basidiocarps. The members are characterized by their saprophytic activities as decomposers, particularly in the degradation of CELLULOSE and LIGNIN. A large number of species in the order have been used medicinally. (From Alexopoulos, Introductory Mycology, 4th ed, pp504-68)Cytokines: Non-antibody proteins secreted by inflammatory leukocytes and some non-leukocytic cells, that act as intercellular mediators. They differ from classical hormones in that they are produced by a number of tissue or cell types rather than by specialized glands. They generally act locally in a paracrine or autocrine rather than endocrine manner.Intestines: The section of the alimentary canal from the STOMACH to the ANAL CANAL. It includes the LARGE INTESTINE and SMALL INTESTINE.Substrate Specificity: A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts.Phytotherapy: Use of plants or herbs to treat diseases or to alleviate pain.Liposomes: 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.Chemistry: A basic science concerned with the composition, structure, and properties of matter; and the reactions that occur between substances and the associated energy exchange.Chromatography, Thin Layer: Chromatography on thin layers of adsorbents rather than in columns. The adsorbent can be alumina, silica gel, silicates, charcoals, or cellulose. (McGraw-Hill Dictionary of Scientific and Technical Terms, 4th ed)Chemical Phenomena: The composition, conformation, and properties of atoms and molecules, and their reaction and interaction processes.Inflammation Mediators: The endogenous compounds that mediate inflammation (AUTACOIDS) and related exogenous compounds including the synthetic prostaglandins (PROSTAGLANDINS, SYNTHETIC).Oxidative Stress: A disturbance in the prooxidant-antioxidant balance in favor of the former, leading to potential damage. Indicators of oxidative stress include damaged DNA bases, protein oxidation products, and lipid peroxidation products (Sies, Oxidative Stress, 1991, pxv-xvi).Lysine: An essential amino acid. It is often added to animal feed.Amino Acids: 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.Tumor Necrosis Factor-alpha: Serum glycoprotein produced by activated MACROPHAGES and other mammalian MONONUCLEAR LEUKOCYTES. It has necrotizing activity against tumor cell lines and increases ability to reject tumor transplants. Also known as TNF-alpha, it is only 30% homologous to TNF-beta (LYMPHOTOXIN), but they share TNF RECEPTORS.Thermodynamics: 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)Spectrometry, Mass, Electrospray Ionization: A mass spectrometry technique used for analysis of nonvolatile compounds such as proteins and macromolecules. The technique involves preparing electrically charged droplets from analyte molecules dissolved in solvent. The electrically charged droplets enter a vacuum chamber where the solvent is evaporated. Evaporation of solvent reduces the droplet size, thereby increasing the coulombic repulsion within the droplet. As the charged droplets get smaller, the excess charge within them causes them to disintegrate and release analyte molecules. The volatilized analyte molecules are then analyzed by mass spectrometry.Electron Spin Resonance Spectroscopy: 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.

Respiratory chain strongly oxidizes the CXXC motif of DsbB in the Escherichia coli disulfide bond formation pathway. (1/630)

Escherichia coli DsbB has four essential cysteine residues, among which Cys41 and Cys44 form a CXXC redox active site motif and the Cys104-Cys130 disulfide bond oxidizes the active site cysteines of DsbA, the disulfide bond formation factor in the periplasm. Functional respiratory chain is required for the cell to keep DsbA oxidized. In this study, we characterized the roles of essential cysteines of DsbB in the coupling with the respiratory chain. Cys104 was found to form the inactive complex with DsbA under respiration-defective conditions. While DsbB, under normal aerobic conditions, is in the oxidized state, having two intramolecular disulfide bonds, oxidation of Cys104 and Cys130 requires the presence of Cys41-Cys44. Remarkably, the Cys41-Cys44 disulfide bond is refractory to reduction by a high concentration of dithiothreitol, unless the membrane is solubilized with a detergent. This reductant resistance requires both the respiratory function and oxygen, since Cys41-Cys44 became sensitive to the reducing agent when membrane was prepared from quinone- or heme-depleted cells or when a membrane sample was deaerated. Thus, the Cys41-Val-Leu-Cys44 motif of DsbB is kept both strongly oxidized and strongly oxidizing when DsbB is integrated into the membrane with the normal set of respiratory components.  (+info)

ApoB100 secretion from HepG2 cells is decreased by the ACAT inhibitor CI-1011: an effect associated with enhanced intracellular degradation of ApoB. (2/630)

The concept that hepatic cholesteryl ester (CE) mass and the rate of cholesterol esterification regulate hepatocyte assembly and secretion of apoB-containing lipoproteins remains controversial. The present study was carried out in HepG2 cells to correlate the rate of cholesterol esterification and CE mass with apoB secretion by CI-1011, an acyl CoA:cholesterol acyltransferase (ACAT) inhibitor that is known to decrease apoB secretion, in vivo, in miniature pigs. HepG2 cells were incubated with CI-1011 (10 nmol/L, 1 micromol/L, and 10 micromol/L) for 24 hours. ApoB secretion into media was decreased by 25%, 27%, and 43%, respectively (P<0.0012). CI-1011 (10 micromol/L) inhibited HepG2 cell ACAT activity by 79% (P<0.002) and cellular CE mass by 32% (P<0.05). In contrast, another ACAT inhibitor, DuP 128 (10 micromol/L), decreased cellular ACAT activity and CE mass by 85% (P<0.002) and 42% (P=0.01), respectively, but had no effect on apoB secretion into media. To characterize the reduction in apoB secretion by CI-1011, pulse-chase experiments were performed and analyzed by multicompartmental modelling using SAAM II. CI-1011 did not affect the synthesis of apoB or albumin. However, apoB secretion into the media was decreased by 42% (P=0.019). Intracellular apoB degradation increased proportionately (P=0.019). The secretion of albumin and cellular reuptake of labeled lipoproteins were unchanged. CI-1011 and DuP 128 did not affect apoB mRNA concentrations. These results show that CI-1011 decreases apoB secretion by a mechanism that involves an enhanced intracellular degradation of apoB. This study demonstrates that ACAT inhibitors can exert differential effects on apoB secretion from HepG2 cells that do not reflect their efficacy in inhibiting cholesterol esterification.  (+info)

Anaerobic oxidations of cysteate: degradation via L-cysteate:2-oxoglutarate aminotransferase in Paracoccus pantotrophus. (3/630)

Anoxic, fresh-water enrichment cultures to oxidize different organosulfonates were set up with nitrate, ferric iron or sulfate as electron acceptors. Pure cultures were easily obtained with two naturally occurring sulfonates, cysteate (2-amino-3-sulfopropionate) and taurine (2-aminoethanesulfonate), under nitrate-reducing conditions. These two sulfonates were also oxidized during reduction of iron(III), though isolation of pure cultures was not successful. One nitrate-reducing cysteate-oxidizing bacterium, strain NKNCYSA, was studied in detail. It was identified as Paracoccus pantotrophus. Eighteen sulfonates were tested, and the organism degraded cysteate, taurine, isethionate (2-hydroxyethanesulfonate), sulfoacetate or 3-aminopropanesulfonate with concomitant reduction of nitrate, presumably to molecular nitrogen. The carbon skeleton of these substrates was converted to cell material and, presumably, CO2. The amino group was released as ammonia and the sulfono moiety was recovered as sulfate. Cell-free extracts of P. pantotrophus NKNCYSA contained constitutive L-cysteate:2-oxoglutarate aminotransferase (EC 2.6.1.-) and glutamate dehydrogenase (EC Taurine:pyruvate aminotransferase, in contrast, was inducible.  (+info)

Modulation of fibroblast growth factor-2 receptor binding, signaling, and mitogenic activity by heparin-mimicking polysulfonated compounds. (4/630)

Basic fibroblast growth factor (FGF-2) interacts with high-affinity tyrosine-kinase fibroblast growth factor receptors (FGFRs) and low-affinity heparan sulfate proteoglycans (HSPGs) in target cells. Both interactions are required for FGF-2-mediated biological responses. Here we report the FGF-2 antagonist activity of novel synthetic sulfonic acid polymers with distinct chemical structures and molecular masses (MMs). PAMPS [poly(2-acrylamido-2-methyl-1-propanesulfonic acid)], (MM approximately 7,000-10,000), PAS [poly(anetholesulfonic acid)], (MM approximately 9,000-11,000), PSS [poly(4-styrenesulfonic acid)], (MM = 70,000), and poly(vinylsulfonic acid) (MM = 2,000), inhibited FGF-2 binding to HSPGs and FGFRs in fetal bovine aortic endothelial GM 7373 cells. They also abrogated the formation of the HSPG/FGF-2/FGFR ternary complex, as evidenced by their capacity to prevent FGF-2-mediated cell-cell attachment of FGFR-1-overexpressing, HSPG-deficient Chinese hamster ovary cells to wild-type HSPG-bearing cells. Direct interaction of the polysulfonates with FGF-2 was demonstrated by their ability to protect the growth factor from proteolytic cleavage. Accordingly, molecular modeling, based on the crystal structure of the interaction of FGF-2 with a heparin hexamer, showed the feasibility of docking PAMPS into the heparin-binding domain of FGF-2. In agreement with their FGF-2-binding capacity, PSS, PAS, and PAMPS inhibited FGF-2-induced cell proliferation in GM 7373 cells and murine brain microvascular endothelial cells. The antiproliferative activity of these compounds was associated with the abrogation of FGF-2-induced tyrosine phosphorylation of FGFR-1. Moreover, the polysulfonates PSS and PAS inhibited FGF-2-induced activation of mitogen-activated protein kinase-1/2, involved in FGF-2 signal transduction. In conclusion, sulfonic acid polymers bind FGF-2 by mimicking heparin interaction. These compounds may provide a tool to inhibit FGF-2-induced endothelial cell proliferation in angiogenesis and tumor growth.  (+info)

Inhibition of ACAT by avasimibe decreases both VLDL and LDL apolipoprotein B production in miniature pigs. (5/630)

An orally bioavailable acyl coenzyme A:cholesterol acyltransferase (ACAT) inhibitor, avasimibe (CI-1011), was used to test the hypothesis that inhibition of cholesterol esterification, in vivo, would reduce hepatic very low density (VLDL) apolipoprotein (apo) B secretion into plasma. ApoB kinetic studies were carried out in 10 control miniature pigs, and in 10 animals treated with avasimibe (10 mg/kg/d, n = 6; 25 mg/kg/d, n = 4). Pigs were fed a diet containing fat (34% of calories) and cholesterol (400 mg/d; 0.1%). Avasimibe decreased the plasma concentrations of total triglyceride, VLDL triglyceride, and VLDL cholesterol by 31;-40% 39-48%, and 31;-35%, respectively. Significant reductions in plasma total cholesterol (35%) and low density lipoprotein (LDL) cholesterol (51%) concentrations were observed only with high dose avasimibe. Autologous 131I-labeled VLDL, 125I-labeled LDL, and [3H]leucine were injected simultaneously into each pig and apoB kinetic data were analyzed using multicompartmental analysis (SAAM II). Avasimibe decreased the VLDL apoB pool size by 40;-43% and the hepatic secretion rate of VLDL apoB by 38;-41%, but did not alter its fractional catabolism. Avasimibe decreased the LDL apoB pool size by 13;-57%, largely due to a dose-dependent 25;-63% in the LDL apoB production rate. Hepatic LDL receptor mRNA abundances were unchanged, consistent with a marginal decrease in LDL apoB FCRs. Hepatic ACAT activity was decreased by 51% (P = 0.050) and 68% (P = 0.087) by low and high dose avasimibe, respectively. The decrease in total apoB secretion correlated with the decrease in hepatic ACAT activity (r = 0.495; P = 0.026). We conclude that inhibition of hepatic ACAT by avasimibe reduces both plasma VLDL and LDL apoB concentrations, primarily by decreasing apoB secretion.  (+info)

Low-molecular-weight sulfonates, a major substrate for sulfate reducers in marine microbial mats. (6/630)

Several low-molecular-weight sulfonates were added to microbial mat slurries to investigate their effects on sulfate reduction. Instantaneous production of sulfide occurred after taurine and cysteate were added to all of the microbial mats tested. The rates of production in the presence of taurine and cysteate were 35 and 24 microM HS(-) h(-1) in a stromatolite mat, 38 and 36 microM HS(-) h(-1) in a salt pond mat, and 27 and 18 microM HS(-) h(-1) in a salt marsh mat, respectively. The traditionally used substrates lactate and acetate stimulated the rate of sulfide production 3 to 10 times more than taurine and cysteate stimulated the rate of sulfide production in all mats, but when ethanol, glycolate, and glutamate were added to stromatolite mat slurries, the resulting increases were similar to the increases observed with taurine and cysteate. Isethionate, sulfosuccinate, and sulfobenzoate were tested only with the stromatolite mat slurry, and these compounds had much smaller effects on sulfide production. Addition of molybdate resulted in a greater inhibitory effect on acetate and lactate utilization than on sulfonate use, suggesting that different metabolic pathways were involved. In all of the mats tested taurine and cysteate were present in the pore water at nanomolar to micromolar concentrations. An enrichment culture from the stromatolite mat was obtained on cysteate in a medium lacking sulfate and incubated anaerobically. The rate of cysteate consumption by this enrichment culture was 1.6 pmol cell(-1) h(-1). Compared to the results of slurry studies, this rate suggests that organisms with properties similar to the properties of this enrichment culture are a major constituent of the sulfidogenic population. In addition, taurine was consumed at some of highest dilutions obtained from most-probable-number enrichment cultures obtained from stromatolite samples. Based on our comparison of the sulfide production rates found in various mats, low-molecular-weight sulfonates are important sources of C and S in these ecosystems.  (+info)

Antioxidant activity: what do we measure? (7/630)

Inhibition of oxidation of 2,2'-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) by free radicals generated by decomposition of 2,2'-azobis(2-amidopropane) (ABAP) by antioxidants and biological material was studied. A correlation was found between the ability of various substances to delay the onset of ABTS oxidation and their rapid reduction of the ABTS+* cation radical, and between the ability to reduce the maximal rate of ABTS oxidation and slow reduction of ABTS+*. The length of the lag period of ABTS oxidation was found to be independent of ABTS concentration. Similar decrease of peroxynitrite-induced ABTS+* formation by antioxidants was observed when the antioxidants were added before and after peroxynitrite. All these findings indicate that the main effect of antioxidants in this system is reduction of ABTS+* and not prevention of its formation. Reduction of oxidation products rather than inhibition of their formation may be the predominant mode of action of antioxidants in various assays of antioxidant activity.  (+info)

Malaria vectors in a traditional dry zone village in Sri Lanka. (8/630)

Malaria transmission by anopheline mosquitoes was studied in a traditional tank-irrigation-based rice-producing village in the malaria-endemic low country dry zone of northcentral Sri Lanka during the period August 1994-February 1997. Adult mosquitoes were collected from human and bovid bait catches, bovid-baited trap huts, indoor catches, and pit traps. Mosquito head-thoraces were tested for the presence of Plasmodium falciparum and P. vivax, and blood-engorged abdomens for the presence of human blood by ELISAs. House surveys were done at two-day intervals to record cases of blood film-confirmed malaria among the villagers. A total of 7,823 female anophelines representing 14 species were collected. Trends in anopheline abundance were significantly correlated with rainfall of the preceding month in An. annularis, An. barbirostris, An. subpictus, An. vagus, and An. varuna, but were not significant in An. culicifacies and An. peditaeniatus. Malaria parasite infections were seen in seven mosquito species, with 75% of the positive mosquitoes containing P. falciparum and 25% P. vivax. Polymorph PV247 was recorded from a vector (i.e., An. varuna) for the first time in Sri Lanka. Computations of mean number of infective vector (MIV) rates using abundance, circumsporozoite (CS) protein rate, and human blood index (HBI) showed the highest rate in An. culicifacies. A malaria outbreak occurred from October 1994 to January 1995 in which 45.5% of village residents experienced at least a single disease episode. Thereafter, malaria incidence remained low. Anopheles culicifacies abundance lagged by one month correlated positively with monthly malaria incidence during the outbreak period, and although this species ranked fifth in terms of abundance, infection was associated with a high MIV rate due to a high CS protein rate and HBI. Abundance trends in other species did not correlate significantly with malaria. It was concluded that An. culicifacies was epidemiologically the most important vector in the study area.  (+info)

  • The esterification of glycerol with lauric and oleic acids (1 : 1 molar ratio) has been carried out by using hybrid MCM-41 materials containing simultaneously alkyl (methyl or propyl) and sulfonic acid groups as catalysts. (
  • The crystal structure of 8-hydroxy-7-iodoquinoline-5-sulfonic acid-urea-water, C9H6INO4S烈4N2O爲O, shows the zwitterionic (quinoline-sulfonate group) ferron molecule lying in a crystallographic mirror plane which related two of the sulfonate O atoms. (
  • Aromatic sulfonic acids are particularly useful as intermediates or starting materials in synthesis-for example, in the preparation of phenols . (
  • Aromatic sulfonic acids are obtained generally by treating aromatic compounds with concentrated sulfuric acid and added sulfur trioxide ("oleum"), the process being called sulfonation . (
  • A particularly large scale application of this method is the production of alkylbenzenesulfonic acids: RC6H5 + SO3 → RC6H4SO3H In this reaction, sulfur trioxide is an electrophile and the arene undergoes electrophilic aromatic substitution. (
  • Although both alkyl and aryl sulfonic acids are known, most of the applications are associated with the aromatic derivatives. (
  • with(B) aromatic isocyanato sulfonic acids, wherein the equivalent ratio of the total quantity of isocyanate groups (including any isocyanate groups present in dimerized form) to sulfonic acid groups is from 0.5:1 to 50:1 and the equivalent ratio of the sum of hydroxyl groups in (A) to NCO groups is from 1.5:1 to 30:1. (
  • The instant invention is directed to a process wherein polyhydroxyl compounds are reacted with sub-equivalent molar quantities of aromatic isocyanatosulfonic acids, optionally in admixture with conventional polyisocyanates. (
  • Linear alkyl benzene sulfonic acid are complex mixtures of homologues of different alkyl chain lengths (C10 to C13 or C14) and phenyl positional isomers of 2 to 5-phenyl in proportions dictated by the starting materials and reaction conditions, each containing an aromatic ring sulfonated at the para position and attached to a linear alkyl chain at any position with the exception of terminal one (1-phenyl). (
  • Two different heterogeneous catalysts carrying aryl-sulfonic moieties, in which the aromatic ring was either fluorinated or not, were successfully synthesized. (
  • A straightforward and efficient method for the synthesis of pyrano[2,3-d]pyrimidine diones derivatives from the reaction of barbituric acid, malononitrile and various aromatic aldehydes using SBA-Pr-SO3H as a nanocatalyst is reported. (
  • Convenient and simple, sequential diazotization-iodination of aromatic amines with NaNO 2 /KI in the presence of a sulfonic acid based cation-exchange resin in water is an inexpensive, noncorrosive and eco-friendly synthetic route, that allows the preparation of various electron-rich and deficient iodoarenes in good yields. (
  • The literature on saturated amino sulfonic acids with primary/secondary amino group and their derivatives from XIX century to 2016 is surveyed, focusing mainly on results published in the last two decades. (
  • Synthesis of saturated amino sulfonic acids and their derivatives, their occurrence among natural products, as well as their use for design of peptidomimetics, conjugates with various molecules of practical significance, applications as building blocks for drug discovery and for other reasons are discussed. (
  • Perfluorooctane sulfonic acid (PFOS) and 3,3′,4,4′,5-pentachlorobiphenyl (PCB126) are persistent organic pollutants of high concern because of their environmental persistence, bioaccumulation and toxic properties. (
  • Exposure modeling results in paper I and II demonstrate that dietary intake is the major exposure pathway of perfluorooctanoic acid (PFOA) and perfluorooctane sulfonic acid (PFOS), while known precursors account for only a few percent of the total exposure. (
  • N-(Iodoacetylaminoethyl)-8-Naphthylamine-1-Sulfonic Acid is a fluorescent sulfhydryl reagent that is sensitive to photo catalyzed degradation in aqueous solution and organic solvents. (
  • Is selective heating of the sulfonic acid catalyst AC-SO3H by microwave radiation crucial in the acid hydrolysis of cellulose to glucose in aqueous media? (
  • The chemically modified guar gum sulphonic acid (GSA) resin was used for removal and pre-concentration of Zn 2+ , Cd 2+ , Fe 2+ , Pb 2+ and Cu 2+ ions in aqueous solutions and steel industry effluent from Jodhpur, India. (
  • Triflic acid, H[OTf], a well-known superacid in aqueous media, has been shown to be a weak acid with a pKa of 2.0 in this ionic liquid. (
  • In the special case of aqueous solutions, proton donors form the hydronium ion H 3 O + and are known as Arrhenius acids . (
  • Aqueous Arrhenius acids have characteristic properties which provide a practical description of an acid. (
  • An aqueous solution of an acid has a pH less than 7 and is colloquially also referred to as 'acid' (as in 'dissolved in acid'), while the strict definition refers only to the solute . (
  • Most acids encountered in everyday life are aqueous solutions , or can be dissolved in water, so the Arrhenius and Brønsted-Lowry definitions are the most relevant. (
  • Triflic acid, one of the strongest known organic acids, is used as a polymerization catalyst and in fuel cells , in gasoline production, and in the synthesis of organic and organometallic compounds . (
  • It is most useful as acid-catalyst reaction such as esterification condensation acetylation polymerization alkylation's hydrolysis dehydration. (
  • Different biomaterials have been chosen, with a view to select the most active solid acid catalyst . (
  • Reduction of the average pore size (determined by N2 adsorption) from 14 to below 10 Å has a detrimental influence on the catalyst activity for both acids. (
  • Kiani Moghadam, Faeze 2016-03-28 00:00:00 This paper reports an efficient heterogeneous catalyst based on sulfonic acid functionalization of magnetic nanoparticles. (
  • This paper reports an efficient heterogeneous catalyst based on sulfonic acid functionalization of magnetic nanoparticles. (
  • The instant invention is directed to compounds having an average molecular weight of from 300 to 12,000, containing: at least one hydroxyl group and at least one urethano-aryl-sulfonic acid group and a method for their preparation. (
  • The process is characterized as a process for the preparation of compounds having a number average molecular weight of from 300 to 12,000 having at least one hydroxyl group and at least one urethano-aryl-sulfonic acid group, comprising: reacting at from (
  • Preliminary results indicated superior performances for the fluoro-aryl-sulfonic acid, compared to the non-fluorinated sample. (
  • Among the various methods used to prepare aliphatic sulfonic acids are the oxidation of other organosulfur compounds, the reaction of alkyl halides and metallic sulfites, and the reaction of organometallic compounds with amine complexes of sulfur trioxide (e.g. (
  • Traditionally, soaps are the popular surfactants, being derived from fatty acids. (
  • A copoly(arylene ether) (PAE) with high fluorine content and a copoly(arylene ether nitrile) (PAEN) with high nitrile content, each containing pendant phenyl sulfonic acids were synthesized. (
  • Sulfonic acid groups can greatly enhance the water solubility of compounds , as seen with the sulfonic acid derivative of triphenyl phosphine (TPPTS), P(C 6 H 4 -m-SO 3 Na) 3 . (
  • Electron deficient heterocycles, such as tetrazole, can be N-aminated with hydroxylamine-O-sulfonic acid, while even more electron-deficient compounds, such as 5-nitrotetrazole, react only with stronger aminating agents such as O-tosylhydroxylamine or O- mesitylene sulfonylhydroxylamine to amino compounds, which were investigated as explosives. (
  • Also sulfur compounds (such as thioethers) can be aminated with hydroxylamine-O-sulfonic acid to sulfinimines (isosteric with sulfoxides but far more unstable) or phosphorus compounds (such as triphenylphosphine) can be aminated to phosphinimines via the intermediate aminotriphenylphosphonium hydrogen sulfate. (
  • and (B) hydroxyl compounds having an average molecular weight of 300 to 12,000 and containing a urethanoaryl-sulfonic acid group, said hydroxyl compounds being prepared by reacting at from (
  • The sulfonic and oxanilic metabolites were present in almost 75% of the groundwater samples and were generally present from 3 to 45 times more frequently than their parent compounds. (
  • PTSA is comparable in strength to mineral acids such as Sulphuric acid, but are especially suitable for organic reactions where an inorganic, mineral acid could cause charring, oxidation, or an unwanted chemical reaction. (
  • Mohammadi, Ali A. Reaction of 4-amino-3-hydroxy-1-naphthalenesulfonic acid with orthoesters: a new facile one-pot synthesis of 2-substituted naphth[1,2-d]oxazole-5-sulfonates. (
  • Although statistically significant temporal trends in the average dietary intake estimates could not be determined, there is preliminary evidence of a downward time trend in the concentrations of PFOS in eggs and meat products and an upward trend of PFDA, PFUnDA, perfluorododecanoic acid and perfluorotridecanoic acid in fish products, which both warrant further investigation. (
  • However, while carboxylic acids are weak (with dissociation constants of about 10 −5 ), sulfonic acids are considered strong acids (with dissociation constants of about 10 −2 ). (
  • Strong acids and some concentrated weak acids are corrosive , but there are exceptions such as carboranes and boric acid . (
  • The net conversion can be represented simplistically: C8H17SO3H + 17 F2 → C8F17SO3H + 17 HF Sulfonic acids are much stronger acids than the corresponding carboxylic acids. (
  • Finally, the pKa values of 10 weak oxyacids, covering 16 orders of magnitude in acid strength (2.0 ≥ pKa ≥ 17.8), have been calculated using a voltammetric method and compared with data from conventional solvents (acetonitrile and water) in order to gain insights into how the nature of the solvent (i.e., dielectric properties, Lewis acidity/basicity, hydrogen donating/accepting ability, etc.) influences equilibrium acidity. (
  • Under basic conditions in the presence of primary amines, hydroxylamine-O-sulfonic acid forms with aldehydes and ketones (e.g. cyclohexanone) diaziridines, which can easily be oxidized to the more stable diazirines. (
  • The parent compound (with the organic substituent replaced by hydrogen) is the hypothetical compound sulfurous acid. (
  • Perfluoroalkyl carboxylic acids (PFCAs) and perfluoroalkane sulfonic acids (PFSAs) are persistent organic contaminants which have been globally measured in human serum samples at low μg L -1 concentrations. (
  • At 80 °C and 100% relative humidity, a 20%-30% enhancement of proton conductivity was only observed when sulfonic acid modified particle less than 50 nm in diameter were used. (
  • Hydrogen evolution from H[OTf] has been simulated using a CE mechanism, where acid dissociation is followed by proton reduction via the classical Volmer-Tafel route. (
  • Proton reduction from a range of other sulfonic or carboxylic acids has been shown to occur in two steps (electron stoichiometry = 1:1), which has been attributed to the formation of a stable intermediate species through homo hydrogen bonding (homoassociation) between the acid and its conjugate anion base. (
  • An acid is a molecule or ion capable of donating a hydron (proton or hydrogen ion H + ), or, alternatively, capable of forming a covalent bond with an electron pair (a Lewis acid). (
  • The first category of acids is the proton donors or Brønsted acids . (
  • unless otherwise specified, acid-base reactions are assumed to involve the transfer of a proton (H + ) from an acid to a base. (
  • The mercapto groups were oxidized to sulfonic acids by heating the membranes in 10 wt % hydrogen peroxide for 1 h. (