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Xanthine Dehydrogenase
Xanthine dehydrogenase, also known as XDH, is a protein that, in humans, is encoded by the ''XDH'' gene. Function Xanthine dehydrogenase belongs to the group of molybdenum-containing hydroxylases involved in the oxidative metabolism of purines. The enzyme is a homodimer. Xanthine dehydrogenase can be converted to xanthine oxidase by reversible sulfhydryl oxidation or by irreversible proteolytic modification. Xanthine dehydrogenase catalyzes the following chemical reaction: xanthine + NAD+ + H2O \rightleftharpoons urate + NADH + H+ The three substrates of this enzyme are xanthine, NAD+, and H2O, whereas its three products are urate, NADH, and H+. This enzyme participates in purine metabolism. Nomenclature This enzyme belongs to the family of oxidoreductases, to be specific, those acting on CH or CH2 groups with NAD+ or NADP+ as acceptor. The systematic name of this enzyme class is xanthine:NAD+ oxidoreductase. Other names in common use include NAD+-xanthine dehy ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Protein
Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific 3D structure that determines its activity. A linear chain of amino acid residues is called a polypeptide. A protein contains at least one long polypeptide. Short polypeptides, containing less than 20–30 residues, are rarely considered to be proteins and are commonly called peptides. The individual amino acid residues are bonded together by peptide bonds and adjacent amino acid residues. The sequence of amino acid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Purine Metabolism
Purine metabolism refers to the metabolic pathways to synthesize and break down purines that are present in many organisms. Biosynthesis Purines are biologically synthesized as nucleotides and in particular as ribotides, i.e. bases attached to ribose 5-phosphate. Both adenine and guanine are derived from the nucleotide inosine monophosphate (IMP), which is the first compound in the pathway to have a completely formed purine ring system. IMP Inosine monophosphate is synthesized on a pre-existing ribose-phosphate through a complex pathway (as shown in the figure on the right). The source of the carbon and nitrogen atoms of the purine ring, 5 and 4 respectively, come from multiple sources. The amino acid glycine contributes all its carbon (2) and nitrogen (1) atoms, with additional nitrogen atoms from glutamine (2) and aspartic acid (1), and additional carbon atoms from formyl groups (2), which are transferred from the coenzyme tetrahydrofolate as 10-formyltetrahydrofolate, and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Molybdenum Enzymes
Molybdenum is a chemical element with the symbol Mo and atomic number 42 which is located in period 5 and group 6. The name is from Neo-Latin ''molybdaenum'', which is based on Ancient Greek ', meaning lead, since its ores were confused with lead ores. Molybdenum minerals have been known throughout history, but the element was discovered (in the sense of differentiating it as a new entity from the mineral salts of other metals) in 1778 by Carl Wilhelm Scheele. The metal was first isolated in 1781 by Peter Jacob Hjelm. Molybdenum does not occur naturally as a free metal on Earth; it is found only in various oxidation states in minerals. The free element, a silvery metal with a grey cast, has the sixth-highest melting point of any element. It readily forms hard, stable carbides in alloys, and for this reason most of the world production of the element (about 80%) is used in steel alloys, including high-strength alloys and superalloys. Most molybdenum compounds have low solubil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Enzymes Of Known Structure
Enzymes () are proteins that act as biological catalysts by accelerating chemical reactions. The molecules upon which enzymes may act are called substrates, and the enzyme converts the substrates into different molecules known as products. Almost all metabolic processes in the cell need enzyme catalysis in order to occur at rates fast enough to sustain life. Metabolic pathways depend upon enzymes to catalyze individual steps. The study of enzymes is called ''enzymology'' and the field of pseudoenzyme analysis recognizes that during evolution, some enzymes have lost the ability to carry out biological catalysis, which is often reflected in their amino acid sequences and unusual 'pseudocatalytic' properties. Enzymes are known to catalyze more than 5,000 biochemical reaction types. Other biocatalysts are catalytic RNA molecules, called ribozymes. Enzymes' specificity comes from their unique three-dimensional structures. Like all catalysts, enzymes increase the reaction ra ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xanthine Oxidase
Xanthine oxidase (XO, sometimes XAO) is a form of xanthine oxidoreductase, a type of enzyme that generates reactive oxygen species. These enzymes catalyze the oxidation of hypoxanthine to xanthine and can further catalyze the oxidation of xanthine to uric acid. These enzymes play an important role in the catabolism of purines in some species, including humans. Xanthine oxidase is defined as an ''enzyme activity'' (EC 1.17.3.2). The same protein, which in humans has the HGNC approved gene symbol ''XDH'', can also have xanthine dehydrogenase activity (EC 1.17.1.4). Most of the protein in the liver exists in a form with xanthine dehydrogenase activity, but it can be converted to xanthine oxidase by reversible sulfhydryl oxidation or by irreversible proteolytic modification. Reaction The following chemical reactions are catalyzed by xanthine oxidase: * hypoxanthine + H2O + O2 \rightleftharpoons xanthine + H2O2 * xanthine + H2O + O2 \rightleftharpoons uric acid + H2O2 * Xanthine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
MOCOS
Molybdenum cofactor sulfurase is an enzyme that in humans is encoded by the ''MOCOS'' gene. MOCOS sulfurates the molybdenum cofactor of xanthine dehydrogenase (XDH) and aldehyde oxidase Aldehyde oxidase (AO) is a metabolizing enzyme, located in the cytosolic compartment of tissues in many organisms. AO catalyzes the oxidation of aldehydes into carboxylic acid, and in addition, catalyzes the hydroxylation of some heterocycles. ... (AOX1), which is required for their enzymatic activities. References Further reading * * * * * EC 2.8.1 {{gene-18-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aldehyde Oxidase And Xanthine Dehydrogenase, A/b Hammerhead Domain
The aldehyde oxidase and xanthine dehydrogenase, a/b hammerhead domain is an evolutionary conserved protein domain. Aldehyde oxidase () catalyzes the conversion of an aldehyde in the presence of oxygen and water to an acid and hydrogen peroxide. The enzyme is a homodimer, and requires FAD, molybdenum and two 2FE-2S clusters as cofactors. Xanthine dehydrogenase () catalyzes the hydrogenation of xanthine to urate, and also requires FAD, molybdenum and two 2FE-2S clusters as cofactors. This activity is often found in a bifunctional enzyme with xanthine oxidase () activity too. The enzyme can be converted from the dehydrogenase form to the oxidase form irreversibly by proteolysis or reversibly through oxidation of sulfhydryl groups. Human proteins containing this domain * AOX1 Aldehyde oxidase 1 is an enzyme that in humans is encoded by the ''AOX1'' gene. Aldehyde oxidase produces hydrogen peroxide and, under certain conditions, can catalyze the formation of superoxide ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Precision Medicine
Precision, precise or precisely may refer to: Science, and technology, and mathematics Mathematics and computing (general) * Accuracy and precision, measurement deviation from true value and its scatter * Significant figures, the number of digits that carry real information about a measurement * Precision and recall, in information retrieval: the proportion of relevant documents returned * Precision (computer science), a measure of the detail in which a quantity is expressed * Precision (statistics), a model parameter or a quantification of precision Computing products * Dell Precision, a line of Dell workstations * Precision Architecture, former name for PA-RISC, a reduced instruction set architecture developed by Hewlett-Packard * Ubuntu 12.04 "Precise Pangolin", Canonical's sixteenth release of Ubuntu Companies * Precision Air, an airline based in Tanzania * Precision Castparts Corp., a casting company based in Portland, Oregon, in the United States * Precision Drill ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adenocarcinoma Of The Lung
Adenocarcinoma of the lung is the most common type of lung cancer, and like other forms of lung cancer, it is characterized by distinct cellular and molecular features. It is classified as one of several non-small cell lung cancers (NSCLC), to distinguish it from small cell lung cancer which has a different behavior and prognosis. Lung adenocarcinoma is further classified into several subtypes and variants. The signs and symptoms of this specific type of lung cancer are similar to other forms of lung cancer, and patients most commonly complain of persistent cough and shortness of breath. Adenocarcinoma is more common in patients with a history of cigarette smoking, and is the most common form of lung cancer in younger women and Asian populations. The pathophysiology of adenocarcinoma is complicated, but generally follows a histologic progression from cells found in healthy lungs to distinctly dysmorphic, or irregular cells. There are several distinct molecular and genetic pathways ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Xanthinuria
Xanthinuria, also known as xanthine oxidase deficiency, is a rare genetic disorder causing the accumulation of xanthine. It is caused by a deficiency of the enzyme xanthine oxidase. It was first formally characterized in 1954. Presentation Sufferers have unusually high concentrations of xanthine in their blood and urine, which can lead to health problems such as renal failure and xanthine kidney stones, one of the rarest types of kidney stones. Causes Type I xanthinuria can be caused by a deficiency of xanthine oxidase, which is an enzyme necessary for converting xanthine to uric acid. Type II xanthinuria and molybdenum cofactor deficiency lack one or two other enzyme activities in addition to xanthine oxidase. Treatment There is no specific treatment beyond maintaining a high fluid intake and avoiding foods that are high in purine Purine is a heterocyclic aromatic organic compound that consists of two rings ( pyrimidine and imidazole) fused together. It is water-soluble. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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