Sulfinic Acids
Oxidoreductases Acting on Sulfur Group Donors
Peroxiredoxins
Cysteine Dioxygenase
Carboxy-Lyases
Taurine
Peroxidases
Oxidation-Reduction
Oxidoreductases
Hydrogen Peroxide
Sulfenic Acids
Catalysis
Spectrometry, Mass, Electrospray Ionization
Selective modification of apoB-100 in the oxidation of low density lipoproteins by myeloperoxidase in vitro. (1/136)
Oxidative modification of LDL may be important in the initiation and/or progression of atherosclerosis, but the precise mechanisms through which low density lipoprotein (LDL) is oxidized are unknown. Recently, evidence for the existence of HOCl-oxidized LDL in human atherosclerotic lesions has been reported, and myeloperoxidase (MPO), which is thought to act through production of HOCl, has been identified in human atherosclerotic lesions. In the present report we describe the formation of 2,4-dinitrophenylhydrazine (DNPH)-reactive modifications in the apolipoprotein (apo) by exposure of LDL to myeloperoxidase in vitro. In contrast with the complex mixture of peptides from oxidation of LDL with reagent HOCl, oxidation with MPO in vitro produced a major tryptic peptide showing absorbance at 365 nm. This peptide was isolated and characterized as VELEVPQL(*C)SFILK..., corresponding to amino acid residues 53-66...on apoB-100. Mass spectrometric analyses of two tryptic peptides from oxidation of LDL by HOCl indicated formation of the corresponding methionine sulfoxide (M=O), cysteinyl azo (*C), RS -N= N-DNP, derivatives of EEL(*C)T(M=O)FIR and LNDLNS VLV(M=O)PTFHVPFTDLQVPS(*C)K, which suggest oxidation to the corresponding sulfinic acids (RSO2H) by HOCl. The present results demonstrate that DNPH-reactive modifications other than aldehydes and ketones can be formed in the oxidation of proteins and illustrate how characterization of specific products of protein oxidation can be useful in assessing the relative contributions of different and unexpected mechanisms to the oxidation of LDL and other target substrates. The data also suggest a direct interaction of the LDL particle with the active site on myeloperoxidase and indicate that effects of the protein microenvironment can greatly influence product formation and stability. (+info)Antimicrobial activity of the thiosulfinates isolated from oil-macerated garlic extract. (2/136)
Three thiosulfinates were isolated from oil-macerated garlic extract, and their structures were identified as 2-propene-1-sulfinothioic acid S-(Z,E)-1-propenyl ester [AllS(O)SPn-(Z,E)], 2-propenesulfinothioic acid S-methyl ester [AllS(O)SMe], and methanesulfinothioic acid S-(Z,E)-1-propenyl ester [MeS(O)SPn-(Z,E)]. This is the first report of isolating these thiosulfinates from oil-macerated garlic extract. Antimicrobial activities of AllS(O)SPn-(Z,E) and AllS(O)SMe against Gram-positive and negative bacteria and yeasts were compared with 2-propene-1-sulfinothioic acid S-2-propenyl ester [AllS(O)SAll, allicin] which is well-known as the major thiosulfinate in garlic. Antimicrobial activity of AllS(O)SMe and AllS(O)SPn-(Z,E) were comparable and inferior to that of allicin, respectively. This result suggested that the antimicrobial activity of 2-propene sulfinothioic acid S-alk(en)yl esters were affected by alk(en)yl groups. The order for antimicrobial activity was: allyl > or = methyl > propenyl. (+info)The mode of action of allicin: its ready permeability through phospholipid membranes may contribute to its biological activity. (3/136)
Allicin (diallyl thiosulfinate) is the main biologically active component of the freshly crushed garlic extracts. In the present work the ability of allicin to cross through membranes (artificial and biological) was studied. Partition coefficients of allicin in water/octanol, water/hexadecane and water/phospholipids mixtures were determined. Using phospholipid vesicles loaded with hydrophilic thiols (reduced glutathione or 2-nitro-5-thiobenzoate), we observed that allicin freely permeates through phospholipid bilayers and interacts with the SH groups. The reaction rate of allicin with SH containing molecules after crossing the membrane was the same as in solution. Fast diffusion and permeation of allicin across human red blood cell membranes was also demonstrated. Allicin does not induce leakage, fusion or aggregation of membrane. The high permeability of allicin through membranes may greatly enhance the intracellular interaction with thiols. (+info)Activities of garlic oil, garlic powder, and their diallyl constituents against Helicobacter pylori. (4/136)
Chronic Helicobacter pylori disease is reduced with Allium vegetable intake. This study was designed to assess the in vivo anti-H. pylori potential of a variety of garlic substances. The garlic materials all showed substantial but widely differing anti-H. pylori effects against all strains and isolates tested. The MICs (range, 8 to 32 microg/ml) and minimum bactericidal concentrations (MBCs) (range, 16 to 32 microg/ml) of undiluted garlic oil (GO) were smaller than those of garlic powder (GP) (MIC range, 250 to 500 microg/ml; MBC range, 250 to 500 microg/ml) but greater than the MIC of allicin (4. 0 microg/ml) (Table 2) present in GP. Allicin (MIC, 6 microg/ml; MBC, 6 microg/ml) was more potent than diallyl disulfide (MIC range, 100 to 200 microg/ml; MBC range, 100 to 200 microg/ml), its corresponding sulfide, but of a strength similar to that of diallyl tetrasulfide (MIC range, 3 to 6 microg/ml; MBC range, 3 to 6 microg/ml). Antimicrobial activity of the diallyl sulfides increased with the number of sulfur atoms. Time course viability studies and microscopy showed dose-dependent anti-H. pylori effects with undiluted GO, GP, allicin, and diallyl trisulfide after a lag phase of ca. 1 to 2 h. Substantial in vitro anti-H. pylori effects of pure GO and GP and their diallyl sulfur components exist, suggesting their potential for in vivo clinical use against H. pylori infections. (+info)Analysis of responses of garlic derivatives in the pulmonary vascular bed of the rat. (5/136)
Allicin, an extract from garlic, has been shown to be a systemic and pulmonary arterial vasodilator that acts by an unknown mechanism. In the present experiments, pulmonary vascular responses to allicin (10-100 microg), allyl mercaptan (0.3-1 mg), and diallyl disulfide (0.3-1 mg) were studied in the isolated lung of the rat under constant-flow conditions. When baseline tone in the pulmonary vascular bed of the rat was raised to a high-steady level with the thromboxane A(2) mimic U-46619, dose-related decreases in pulmonary arterial pressure were observed. In terms of the mechanism of action of allicin vasodilator activity in the rat, responses to allicin were not significantly different after administration of the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine methyl ester, the K(ATP)(+) channel antagonist U-37883A, or the cyclooxygenase inhibitor sodium meclofenamate, or when lung ventilation was interrupted. These data show that allicin has significant vasodilator activity in the pulmonary vascular bed of the rat, whereas allyl mercaptan and diallyl disulfide produced no significant changes in pulmonary arterial perfusion pressure. The present data suggest that pulmonary vasodilator responses to allicin are independent of the synthesis of nitric oxide, ATP-sensitive K(+) channels, activation of cyclooxygenase enzyme, or changes in bronchomotor tone in the pulmonary vascular bed of the rat. (+info)S-Allylmercaptoglutathione: the reaction product of allicin with glutathione possesses SH-modifying and antioxidant properties. (6/136)
The reaction between allicin (diallylthiosulfinate), the active component of garlic and reduced glutathione was investigated. The product of this reaction, mixed disulfide S-allylmercaptoglutathione (GSSA) was separated by high performance liquid chromatography and identified by 1H and (13)C nuclear magnetic resonance and mass spectroscopy. The reaction is fast (with an apparent bimolecular reaction rate constant of 3.0 M(-1) s(-1)). It is pH-dependent, which reveals a direct correlation to the actual concentration of mercaptide ion (GS(-)). Both GSSA and S-allylmercaptocysteine (prepared from allicin and cysteine) reacted with SH-containing enzymes, papain and alcohol dehydrogenase from Thermoanaerobium brockii yielding the corresponding S-allylmercapto proteins, and caused inactivation of the enzymes. The activity was restored with dithiothreitol or 2-mercaptoethanol. In addition, GSSA also exhibited high antioxidant properties. It showed significant inhibition of the reaction between OH radicals and the spin trap 5,5'-dimethyl-1-pyroline N-oxide in the Fenton system as well as in the UV photolysis of H2O2. In ex vivo experiments done with fetal brain slices under iron-induced oxidative stress, GSSA significantly lowered the production levels of lipid peroxides. The similar activity of GSSA and allicin as SH-modifiers and antioxidants suggests that the thioallyl moiety has a key role in the biological activity of allicin and its derivatives. (+info)Intake of garlic and its bioactive components. (7/136)
The health benefits of garlic likely arise from a wide variety of components, possibly working synergistically. The complex chemistry of garlic makes it plausible that variations in processing can yield quite different preparations. Highly unstable thiosulfinates, such as allicin, disappear during processing and are quickly transformed into a variety of organosulfur components. The efficacy and safety of these preparations in preparing dietary supplements based on garlic are also contingent on the processing methods employed. Although there are many garlic supplements commercially available, they fall into one of four categories, i.e., dehydrated garlic powder, garlic oil, garlic oil macerate and aged garlic extract (AGE). Garlic and garlic supplements are consumed in many cultures for their hypolipidemic, antiplatelet and procirculatory effects. In addition to these proclaimed beneficial effects, some garlic preparations also appear to possess hepatoprotective, immune-enhancing, anticancer and chemopreventive activities. Some preparations appear to be antioxidative, whereas others may stimulate oxidation. These additional biological effects attributed to AGE may be due to compounds, such as S-allylcysteine, S-allylmercaptocysteine, N(alpha)-fructosyl arginine and others, formed during the extraction process. Although not all of the active ingredients are known, ample research suggests that several bioavailable components likely contribute to the observed beneficial effects of garlic. (+info)Determination of allicin, S-allylcysteine and volatile metabolites of garlic in breath, plasma or simulated gastric fluids. (8/136)
Various components of garlic and aged garlic extract, including allicin, S-allylcysteine (SAC) and volatile metabolites of allicin were determined in breath, plasma and simulated gastric fluids by HPLC, gas chromatography (GC) or HPLC- and GC-mass spectrometry (MS). Data indicate that allicin decomposes in stomach acid to release allyl sulfides, disulfides and other volatiles that are postulated to be metabolized by glutathione and/or S-adenosylmethionine to form allyl methyl sulfide. SAC can be absorbed by the body and can be determined in plasma by HPLC or HPLC-MS using atmospheric pressure chemical ionization (APCI)-MS. (+info)I apologize for any confusion, but "Sulfinic Acids" is not a term used in medical definitions. It is a term from the field of chemistry. Sulfinic acids are organic compounds that contain a functional group with the formula RSO(O)H, where R represents an alkyl or aryl group. They are important intermediates in organic synthesis and can be found in some natural sources. If you have any questions related to medical terminology or concepts, I would be happy to help!
Oxidoreductases acting on sulfur group donors are a class of enzymes that catalyze redox reactions involving sulfur group donors. These enzymes play a crucial role in various biological processes, such as the metabolism of sulfur-containing compounds and the detoxification of xenobiotics.
The term "oxidoreductase" refers to any enzyme that catalyzes an oxidation-reduction reaction, where one molecule is oxidized (loses electrons) and another is reduced (gains electrons). In the case of oxidoreductases acting on sulfur group donors, the sulfur atom in the substrate serves as the electron donor.
The systematic name for this class of enzymes follows a specific format: "donor:acceptor oxidoreductase." The donor is the sulfur-containing compound that donates electrons, and the acceptor is the molecule that accepts the electrons. For example, the enzyme that catalyzes the reaction between glutathione (GSH) and a variety of electrophiles is called glutathione transferase, or GST (donor:acceptor oxidoreductase).
These enzymes are further classified into subclasses based on the type of acceptor involved in the reaction. Examples include:
* EC 1.8.1: Oxidoreductases acting on CH-NH2 group donors
* EC 1.8.3: Oxidoreductases acting on CH or CH2 groups
* EC 1.8.4: Oxidoreductases acting on the CH-CH group of donors
* EC 1.8.5: Oxidoreductases acting on a sulfur group of donors
* EC 1.8.6: Oxidoreductases acting on NADH or NADPH
The subclass EC 1.8.5, oxidoreductases acting on a sulfur group of donors, includes enzymes that catalyze redox reactions involving sulfur-containing compounds such as thiols (compounds containing -SH groups), disulfides (-S-S- bonds), and other sulfur-containing functional groups. These enzymes play crucial roles in various biological processes, including detoxification, antioxidant defense, and redox regulation.
Peroxiredoxins (Prx) are a family of peroxidases that play a crucial role in cellular defense against oxidative stress. They catalyze the reduction of hydrogen peroxide, organic hydroperoxides, and peroxynitrite, thereby protecting cells from potentially harmful effects of these reactive oxygen and nitrogen species.
Peroxiredoxins are ubiquitously expressed in various cellular compartments, including the cytosol, mitochondria, and nucleus. They contain a conserved catalytic cysteine residue that gets oxidized during the reduction of peroxides, which is then reduced back to its active form by thioredoxins or other reducing agents.
Dysregulation of peroxiredoxin function has been implicated in various pathological conditions, including cancer, neurodegenerative diseases, and inflammatory disorders. Therefore, understanding the role of peroxiredoxins in cellular redox homeostasis is essential for developing novel therapeutic strategies to treat oxidative stress-related diseases.
Cysteine is a semi-essential amino acid, which means that it can be produced by the human body under normal circumstances, but may need to be obtained from external sources in certain conditions such as illness or stress. Its chemical formula is HO2CCH(NH2)CH2SH, and it contains a sulfhydryl group (-SH), which allows it to act as a powerful antioxidant and participate in various cellular processes.
Cysteine plays important roles in protein structure and function, detoxification, and the synthesis of other molecules such as glutathione, taurine, and coenzyme A. It is also involved in wound healing, immune response, and the maintenance of healthy skin, hair, and nails.
Cysteine can be found in a variety of foods, including meat, poultry, fish, dairy products, eggs, legumes, nuts, seeds, and some grains. It is also available as a dietary supplement and can be used in the treatment of various medical conditions such as liver disease, bronchitis, and heavy metal toxicity. However, excessive intake of cysteine may have adverse effects on health, including gastrointestinal disturbances, nausea, vomiting, and headaches.
Cysteine dioxygenase (CDO) is an enzyme that catalyzes the conversion of the amino acid L-cysteine to L-cysteinesulfinic acid, which is the first step in the catabolism of L-cysteine. This reaction also generates molecular oxygen as a byproduct. CDO plays important roles in various biological processes such as neurotransmitter biosynthesis and oxidative stress response. It exists as two isoforms, CDO1 and CDO2, which are encoded by separate genes and have distinct tissue distributions and functions.
Carboxy-lyases are a class of enzymes that catalyze the removal of a carboxyl group from a substrate, often releasing carbon dioxide in the process. These enzymes play important roles in various metabolic pathways, such as the biosynthesis and degradation of amino acids, sugars, and other organic compounds.
Carboxy-lyases are classified under EC number 4.2 in the Enzyme Commission (EC) system. They can be further divided into several subclasses based on their specific mechanisms and substrates. For example, some carboxy-lyases require a cofactor such as biotin or thiamine pyrophosphate to facilitate the decarboxylation reaction, while others do not.
Examples of carboxy-lyases include:
1. Pyruvate decarboxylase: This enzyme catalyzes the conversion of pyruvate to acetaldehyde and carbon dioxide during fermentation in yeast and other organisms.
2. Ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO): This enzyme is essential for photosynthesis in plants and some bacteria, as it catalyzes the fixation of carbon dioxide into an organic molecule during the Calvin cycle.
3. Phosphoenolpyruvate carboxylase: Found in plants, algae, and some bacteria, this enzyme plays a role in anaplerotic reactions that replenish intermediates in the citric acid cycle. It catalyzes the conversion of phosphoenolpyruvate to oxaloacetate and inorganic phosphate.
4. Aspartate transcarbamylase: This enzyme is involved in the biosynthesis of pyrimidines, a class of nucleotides. It catalyzes the transfer of a carboxyl group from carbamoyl aspartate to carbamoyl phosphate, forming cytidine triphosphate (CTP) and fumarate.
5. Urocanase: Found in animals, this enzyme is involved in histidine catabolism. It catalyzes the conversion of urocanate to formiminoglutamate and ammonia.
Taurine is an organic compound that is widely distributed in animal tissues. It is a conditionally essential amino acid, meaning it can be synthesized by the human body under normal circumstances, but there may be increased requirements during certain periods such as infancy, infection, or illness. Taurine plays important roles in various physiological functions, including bile salt formation, membrane stabilization, neuromodulation, and antioxidation. It is particularly abundant in the brain, heart, retina, and skeletal muscles. In the human body, taurine is synthesized from the amino acids cysteine and methionine with the aid of vitamin B6.
Taurine can also be found in certain foods like meat, fish, and dairy products, as well as in energy drinks, where it is often added as a supplement for its potential performance-enhancing effects. However, there is ongoing debate about the safety and efficacy of taurine supplementation in healthy individuals.
Peroxidases are a group of enzymes that catalyze the oxidation of various substrates using hydrogen peroxide (H2O2) as the electron acceptor. These enzymes contain a heme prosthetic group, which plays a crucial role in their catalytic activity. Peroxidases are widely distributed in nature and can be found in plants, animals, and microorganisms. They play important roles in various biological processes, including defense against oxidative stress, lignin degradation, and host-pathogen interactions. Some common examples of peroxidases include glutathione peroxidase, which helps protect cells from oxidative damage, and horseradish peroxidase, which is often used in laboratory research.
Oxidation-Reduction (redox) reactions are a type of chemical reaction involving a transfer of electrons between two species. The substance that loses electrons in the reaction is oxidized, and the substance that gains electrons is reduced. Oxidation and reduction always occur together in a redox reaction, hence the term "oxidation-reduction."
In biological systems, redox reactions play a crucial role in many cellular processes, including energy production, metabolism, and signaling. The transfer of electrons in these reactions is often facilitated by specialized molecules called electron carriers, such as nicotinamide adenine dinucleotide (NAD+/NADH) and flavin adenine dinucleotide (FAD/FADH2).
The oxidation state of an element in a compound is a measure of the number of electrons that have been gained or lost relative to its neutral state. In redox reactions, the oxidation state of one or more elements changes as they gain or lose electrons. The substance that is oxidized has a higher oxidation state, while the substance that is reduced has a lower oxidation state.
Overall, oxidation-reduction reactions are fundamental to the functioning of living organisms and are involved in many important biological processes.
Oxidoreductases are a class of enzymes that catalyze oxidation-reduction reactions, which involve the transfer of electrons from one molecule (the reductant) to another (the oxidant). These enzymes play a crucial role in various biological processes, including energy production, metabolism, and detoxification.
The oxidoreductase-catalyzed reaction typically involves the donation of electrons from a reducing agent (donor) to an oxidizing agent (acceptor), often through the transfer of hydrogen atoms or hydride ions. The enzyme itself does not undergo any permanent chemical change during this process, but rather acts as a catalyst to lower the activation energy required for the reaction to occur.
Oxidoreductases are classified and named based on the type of electron donor or acceptor involved in the reaction. For example, oxidoreductases that act on the CH-OH group of donors are called dehydrogenases, while those that act on the aldehyde or ketone groups are called oxidases. Other examples include reductases, peroxidases, and catalases.
Understanding the function and regulation of oxidoreductases is important for understanding various physiological processes and developing therapeutic strategies for diseases associated with impaired redox homeostasis, such as cancer, neurodegenerative disorders, and cardiovascular disease.
Hydrogen peroxide (H2O2) is a colorless, odorless, clear liquid with a slightly sweet taste, although drinking it is harmful and can cause poisoning. It is a weak oxidizing agent and is used as an antiseptic and a bleaching agent. In diluted form, it is used to disinfect wounds and kill bacteria and viruses on the skin; in higher concentrations, it can be used to bleach hair or remove stains from clothing. It is also used as a propellant in rocketry and in certain industrial processes. Chemically, hydrogen peroxide is composed of two hydrogen atoms and two oxygen atoms, and it is structurally similar to water (H2O), with an extra oxygen atom. This gives it its oxidizing properties, as the additional oxygen can be released and used to react with other substances.
I'm sorry for any confusion, but "Sulfenic Acids" is not a term used in medical definitions. Sulfenic acids are organic compounds that contain a functional group with the structure R-SOH, where R represents an alkyl or aryl group. They are important intermediates in organic chemistry and biochemistry, but they are not directly related to medical terminology or human health conditions.
Catalysis is the process of increasing the rate of a chemical reaction by adding a substance known as a catalyst, which remains unchanged at the end of the reaction. A catalyst lowers the activation energy required for the reaction to occur, thereby allowing the reaction to proceed more quickly and efficiently. This can be particularly important in biological systems, where enzymes act as catalysts to speed up metabolic reactions that are essential for life.
Mass spectrometry with electrospray ionization (ESI-MS) is an analytical technique used to identify and quantify chemical species in a sample based on the mass-to-charge ratio of charged particles. In ESI-MS, analytes are ionized through the use of an electrospray, where a liquid sample is introduced through a metal capillary needle at high voltage, creating an aerosol of charged droplets. As the solvent evaporates, the analyte molecules become charged and can be directed into a mass spectrometer for analysis.
ESI-MS is particularly useful for the analysis of large biomolecules such as proteins, peptides, and nucleic acids, due to its ability to gently ionize these species without fragmentation. The technique provides information about the molecular weight and charge state of the analytes, which can be used to infer their identity and structure. Additionally, ESI-MS can be interfaced with separation techniques such as liquid chromatography (LC) for further purification and characterization of complex samples.
Peroxiredoxin VI (Prdx6) is an antioxidant enzyme that belongs to the peroxiredoxin family. It plays a crucial role in reducing and regulating the levels of hydrogen peroxide, lipid peroxides, and other reactive oxygen species (ROS) within cells. Prdx6 has both peroxidase and phospholipase A2 activities, which makes it unique among the peroxiredoxins. It is widely expressed in various tissues, including the lungs, liver, kidneys, and brain. In addition to its antioxidant function, Prdx6 also contributes to cellular signaling pathways, inflammation regulation, and membrane repair processes. Dysregulation of Prdx6 has been implicated in several diseases, such as cancer, neurodegenerative disorders, and lung injury.