Peroxidases
Peroxidases are enzymes that catalyze the reduction of hydrogen peroxide to water, while oxidizing various organic and inorganic compounds, playing crucial roles in diverse biological processes including stress response, immune defense, and biosynthetic reactions.
Horseradish Peroxidase
Glutathione Peroxidase
An enzyme catalyzing the oxidation of 2 moles of glutathione in the presence of hydrogen peroxide to yield oxidized glutathione and water. EC 1.11.1.9.
Peroxidase
Cytochrome-c Peroxidase
A hemeprotein which catalyzes the oxidation of ferrocytochrome c to ferricytochrome c in the presence of hydrogen peroxide. EC 1.11.1.5.
Ascorbate Peroxidases
Peroxidases that utilize ASCORBIC ACID as an electron donor to reduce HYDROGEN PEROXIDE to WATER. The reaction results in the production of monodehydroascorbic acid and DEHYDROASCORBIC ACID.
Eosinophil Peroxidase
A 66-kDa peroxidase found in EOSINOPHIL granules. Eosinophil peroxidase is a cationic protein with a pI of 10.8 and is comprised of a heavy chain subunit and a light chain subunit. It possesses cytotoxic activity towards BACTERIA and other organisms, which is attributed to its peroxidase activity.
Iodide Peroxidase
Hydrogen Peroxide
Guaiacol
Catalase
An oxidoreductase that catalyzes the conversion of HYDROGEN PEROXIDE to water and oxygen. It is present in many animal cells. A deficiency of this enzyme results in ACATALASIA.
Selenium
An element with the atomic symbol Se, atomic number 34, and atomic weight 78.96. It is an essential micronutrient for mammals and other animals but is toxic in large amounts. Selenium protects intracellular structures against oxidative damage. It is an essential component of GLUTATHIONE PEROXIDASE.
Lactoperoxidase
Peroxiredoxins
A family of ubiquitously-expressed peroxidases that play a role in the reduction of a broad spectrum of PEROXIDES like HYDROGEN PEROXIDE; LIPID PEROXIDES and peroxinitrite. They are found in a wide range of organisms, such as BACTERIA; PLANTS; and MAMMALS. The enzyme requires the presence of a thiol-containing intermediate such as THIOREDOXIN as a reducing cofactor.
Lignin
The most abundant natural aromatic organic polymer found in all vascular plants. Lignin together with cellulose and hemicellulose are the major cell wall components of the fibers of all wood and grass species. Lignin is composed of coniferyl, p-coumaryl, and sinapyl alcohols in varying ratios in different plant species. (From Merck Index, 11th ed)
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).
Superoxide Dismutase
An oxidoreductase that catalyzes the reaction between superoxide anions and hydrogen to yield molecular oxygen and hydrogen peroxide. The enzyme protects the cell against dangerous levels of superoxide. EC 1.15.1.1.
Chloride Peroxidase
Basidiomycota
Benzyl Alcohols
Antioxidants
Glutathione Reductase
Catalyzes the oxidation of GLUTATHIONE to GLUTATHIONE DISULFIDE in the presence of NADP+. Deficiency in the enzyme is associated with HEMOLYTIC ANEMIA. Formerly listed as EC 1.6.4.2.
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).
Heme
The color-furnishing portion of hemoglobin. It is found free in tissues and as the prosthetic group in many hemeproteins.
Peroxides
A group of compounds that contain a bivalent O-O group, i.e., the oxygen atoms are univalent. They can either be inorganic or organic in nature. Such compounds release atomic (nascent) oxygen readily. Thus they are strong oxidizing agents and fire hazards when in contact with combustible materials, especially under high-temperature conditions. The chief industrial uses of peroxides are as oxidizing agents, bleaching agents, and initiators of polymerization. (From Hawley's Condensed Chemical Dictionary, 11th ed)
Glutathione
A tripeptide with many roles in cells. It conjugates to drugs to make them more soluble for excretion, is a cofactor for some enzymes, is involved in protein disulfide bond rearrangement and reduces peroxides.
Histocytochemistry
Lipid Peroxidation
Peroxidase catalyzed oxidation of lipids using hydrogen peroxide as an electron acceptor.
Spectrophotometry
Phanerochaete
A genus of fungi in the family Corticiaceae, order Stereales, that degrades lignin. The white-rot fungus Phanerochaete chrysosporium is a frequently used species in research.
Benzidines
Very toxic industrial chemicals. They are absorbed through the skin, causing lethal blood, bladder, liver, and kidney damage and are potent, broad-spectrum carcinogens in most species.
Coprinus
A genus of black-spored basidiomycetous fungi of the family Coprinaceae, order Agaricales; some species are edible.
Selenoproteins
Selenoproteins are proteins that specifically incorporate SELENOCYSTEINE into their amino acid chain. Most selenoproteins are enzymes with the selenocysteine residues being responsible for their catalytic functions.
Lipid Peroxides
Peroxides produced in the presence of a free radical by the oxidation of unsaturated fatty acids in the cell in the presence of molecular oxygen. The formation of lipid peroxides results in the destruction of the original lipid leading to the loss of integrity of the membranes. They therefore cause a variety of toxic effects in vivo and their formation is considered a pathological process in biological systems. Their formation can be inhibited by antioxidants, such as vitamin E, structural separation or low oxygen tension.
Wheat Germ Agglutinin-Horseradish Peroxidase Conjugate
The lectin wheatgerm agglutinin conjugated to the enzyme HORSERADISH PEROXIDASE. It is widely used for tracing neural pathways.
Pleurotus
A genus of basidiomycetous fungi, family POLYPORACEAE, order POLYPORALES, that grows on logs or tree stumps in shelflike layers. The species P. ostreatus, the oyster mushroom, is a choice edible species and is the most frequently encountered member of the genus in eastern North America. (Alexopoulos et al., Introductory Mycology, 4th ed, p531)
Selenious Acid
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.
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.
Peroxiredoxin VI
Catalysis
Thyroid Gland
A highly vascularized endocrine gland consisting of two lobes joined by a thin band of tissue with one lobe on each side of the TRACHEA. It secretes THYROID HORMONES from the follicular cells and CALCITONIN from the parafollicular cells thereby regulating METABOLISM and CALCIUM level in blood, respectively.
3,3'-Diaminobenzidine
Amino Acid Sequence
Hydrogen-Ion Concentration
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.
Peroxiredoxin III
A THIOREDOXIN-dependent hydroperoxidase that is localized in the mitochondrial matrix. The enzyme plays a crucial role in protecting mitochondrial components from elevated levels of HYDROGEN PEROXIDE.
Selenoprotein P
An extracellular selenoprotein that contains most of the SELENIUM in PLASMA. Selenoprotein P functions as an antioxidant and appears to transport selenium from the LIVER to peripheral tissues.
Isoenzymes
Hemeproteins
Proteins that contain an iron-porphyrin, or heme, prosthetic group resembling that of hemoglobin. (From Lehninger, Principles of Biochemistry, 1982, p480)
Selenocysteine
A naturally occurring amino acid in both eukaryotic and prokaryotic organisms. It is found in tRNAs and in the catalytic site of some enzymes. The genes for glutathione peroxidase and formate dehydrogenase contain the TGA codon, which codes for this amino acid.
Polyporaceae
A family of bracket fungi, order POLYPORALES, living in decaying plant matter and timber.
Microscopy, Electron
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.
Ascorbic Acid
A six carbon compound related to glucose. It is found naturally in citrus fruits and many vegetables. Ascorbic acid is an essential nutrient in human diets, and necessary to maintain connective tissue and bone. Its biologically active form, vitamin C, functions as a reducing agent and coenzyme in several metabolic pathways. Vitamin C is considered an antioxidant.
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)
Reactive Oxygen Species
Molecules or ions formed by the incomplete one-electron reduction of oxygen. These reactive oxygen intermediates include SINGLET OXYGEN; SUPEROXIDES; PEROXIDES; HYDROXYL RADICAL; and HYPOCHLOROUS ACID. They contribute to the microbicidal activity of PHAGOCYTES, regulation of signal transduction and gene expression, and the oxidative damage to NUCLEIC ACIDS; PROTEINS; and LIPIDS.
Thiobarbituric Acid Reactive Substances
Low-molecular-weight end products, probably malondialdehyde, that are formed during the decomposition of lipid peroxidation products. These compounds react with thiobarbituric acid to form a fluorescent red adduct.
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)
Glucose Oxidase
An enzyme of the oxidoreductase class that catalyzes the conversion of beta-D-glucose and oxygen to D-glucono-1,5-lactone and peroxide. It is a flavoprotein, highly specific for beta-D-glucose. The enzyme is produced by Penicillium notatum and other fungi and has antibacterial activity in the presence of glucose and oxygen. It is used to estimate glucose concentration in blood or urine samples through the formation of colored dyes by the hydrogen peroxide produced in the reaction. (From Enzyme Nomenclature, 1992) EC 1.1.3.4.
Cyanides
Eosinophils
Enzymes, Immobilized
Manganese
A trace element with atomic symbol Mn, atomic number 25, and atomic weight 54.94. It is concentrated in cell mitochondria, mostly in the pituitary gland, liver, pancreas, kidney, and bone, influences the synthesis of mucopolysaccharides, stimulates hepatic synthesis of cholesterol and fatty acids, and is a cofactor in many enzymes, including arginase and alkaline phosphatase in the liver. (From AMA Drug Evaluations Annual 1992, p2035)
Glutathione Transferase
A transferase that catalyzes the addition of aliphatic, aromatic, or heterocyclic FREE RADICALS as well as EPOXIDES and arene oxides to GLUTATHIONE. Addition takes place at the SULFUR. It also catalyzes the reduction of polyol nitrate by glutathione to polyol and nitrite.
Agaricales
tert-Butylhydroperoxide
Armoracia
A plant genus of the family BRASSICACEAE known for the root used in hot SPICES. It is also the source of HORSERADISH PEROXIDASE which is widely used in laboratories.
Thyroglobulin
Oxygen
Substrate Specificity
Oxidants
Electron-accepting molecules in chemical reactions in which electrons are transferred from one molecule to another (OXIDATION-REDUCTION).
Liver
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.
Spectrum Analysis, Raman
Pinocytosis
Immunoenzyme Techniques
Glutathione Disulfide
A GLUTATHIONE dimer formed by a disulfide bond between the cysteine sulfhydryl side chains during the course of being oxidized.
Anisoles
Spectrophotometry, Ultraviolet
Sodium Selenite
The disodium salt of selenious acid. It is used therapeutically to supply the trace element selenium and is prepared by the reaction of SELENIUM DIOXIDE with SODIUM HYDROXIDE.
Amitrole
A non-selective post-emergence, translocated herbicide. According to the Seventh Annual Report on Carcinogens (PB95-109781, 1994) this substance may reasonably be anticipated to be a carcinogen. (From Merck Index, 12th ed) It is an irreversible inhibitor of CATALASE, and thus impairs activity of peroxisomes.
Erythrocytes
Red blood cells. Mature erythrocytes are non-nucleated, biconcave disks containing HEMOGLOBIN whose function is to transport OXYGEN.
Benzene Derivatives
Thyroiditis, Autoimmune
Inflammatory disease of the THYROID GLAND due to autoimmune responses leading to lymphocytic infiltration of the gland. It is characterized by the presence of circulating thyroid antigen-specific T-CELLS and thyroid AUTOANTIBODIES. The clinical signs can range from HYPOTHYROIDISM to THYROTOXICOSIS depending on the type of autoimmune thyroiditis.
Plants
Multicellular, eukaryotic life forms of kingdom Plantae (sensu lato), comprising the VIRIDIPLANTAE; RHODOPHYTA; and GLAUCOPHYTA; all of which acquired chloroplasts by direct endosymbiosis of CYANOBACTERIA. They are characterized by a mainly photosynthetic mode of nutrition; essentially unlimited growth at localized regions of cell divisions (MERISTEMS); cellulose within cells providing rigidity; the absence of organs of locomotion; absence of nervous and sensory systems; and an alternation of haploid and diploid generations.
Bromides
Vitamin E
A generic descriptor for all TOCOPHEROLS and TOCOTRIENOLS that exhibit ALPHA-TOCOPHEROL activity. By virtue of the phenolic hydrogen on the 2H-1-benzopyran-6-ol nucleus, these compounds exhibit varying degree of antioxidant activity, depending on the site and number of methyl groups and the type of ISOPRENOIDS.
Thioredoxins
Hydrogen-donating proteins that participates in a variety of biochemical reactions including ribonucleotide reduction and reduction of PEROXIREDOXINS. Thioredoxin is oxidized from a dithiol to a disulfide when acting as a reducing cofactor. The disulfide form is then reduced by NADPH in a reaction catalyzed by THIOREDOXIN REDUCTASE.
Chromatography, High Pressure Liquid
Organoselenium Compounds
Organic compounds which contain selenium as an integral part of the molecule.
Thioredoxin-Disulfide Reductase
A FLAVOPROTEIN enzyme that catalyzes the oxidation of THIOREDOXINS to thioredoxin disulfide in the presence of NADP+. It was formerly listed as EC 1.6.4.5
Prostaglandins G
Spectrum Analysis
Base Sequence
Models, Chemical
Models, Molecular
Plant Proteins
Proteins found in plants (flowers, herbs, shrubs, trees, etc.). The concept does not include proteins found in vegetables for which VEGETABLE PROTEINS is available.
Plant Leaves
Expanded structures, usually green, of vascular plants, characteristically consisting of a bladelike expansion attached to a stem, and functioning as the principal organ of photosynthesis and transpiration. (American Heritage Dictionary, 2d ed)
Phenylhydrazines
Asparagus Plant
Coumaric Acids
Hydroxycinnamic acid and its derivatives. Act as activators of the indoleacetic acid oxidizing system, thereby producing a decrease in the endogenous level of bound indoleacetic acid in plants.
Biocatalysis
Binding Sites
Gene Expression Regulation, Enzymologic
Sodium Azide
Electrophoresis, Polyacrylamide Gel
Cloning, Molecular
Sequence Homology, Amino Acid
Diiodotyrosine
A product from the iodination of MONOIODOTYROSINE. In the biosynthesis of thyroid hormones, diiodotyrosine residues are coupled with other monoiodotyrosine or diiodotyrosine residues to form T4 or T3 thyroid hormones (THYROXINE and TRIIODOTHYRONINE).