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Flavoprotein Enzymes
Flavoproteins are proteins that contain a nucleic acid derivative of riboflavin. These proteins are involved in a wide array of biological processes, including removal of radicals contributing to oxidative stress, photosynthesis, and DNA repair. The flavoproteins are some of the most-studied families of enzymes. Flavoproteins have either FMN (flavin mononucleotide) or FAD (flavin adenine dinucleotide) as a prosthetic group or as a cofactor. The flavin is generally tightly bound (as in adrenodoxin reductase, wherein the FAD is buried deeply). About 5-10% of flavoproteins have a covalently linked FAD. Based on the available structural data, FAD-binding sites can be divided into more than 200 different types. 90 flavoproteins are encoded in the human genome; about 84% require FAD and around 16% require FMN, whereas 5 proteins require both. Flavoproteins are mainly located in the mitochondria. Of all flavoproteins, 90% perform redox reactions and the other 10% are transferases, lyas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Proteins
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] |
Enzyme
An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different molecules known as product (chemistry), products. Almost all metabolism, metabolic processes in the cell (biology), 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, 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 include Ribozyme, catalytic RNA molecules, also called ribozymes. They are sometimes descr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biosynthesis
Biosynthesis, i.e., chemical synthesis occurring in biological contexts, is a term most often referring to multi-step, enzyme-Catalysis, catalyzed processes where chemical substances absorbed as nutrients (or previously converted through biosynthesis) serve as enzyme substrate (chemistry), substrates, with conversion by the living organism either into simpler or more complex Product (chemistry), products. Examples of biosynthetic pathways include those for the production of amino acids, lipid membrane components, and nucleotides, but also for the production of all classes of biological macromolecules, and of acetyl-coenzyme A, adenosine triphosphate, nicotinamide adenine dinucleotide and other key intermediate and transactional molecules needed for metabolism. Thus, in biosynthesis, any of an array of Chemical compound, compounds, from simple to complex, are converted into other compounds, and so it includes both the catabolism and anabolism (building up and breaking down) of comple ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cytochrome P450 Reductase
Cytochrome P450 reductase (also known as NADPH:ferrihemoprotein oxidoreductase, NADPH:hemoprotein oxidoreductase, NADPH:P450 oxidoreductase, P450 reductase, POR, CPR, CYPOR) is a membrane-bound enzyme required for electron transfer from NADPH to cytochrome P450 and other heme proteins including heme oxygenase in the endoplasmic reticulum of the eukaryotic cell. Gene Human POR gene has 16 exons and the exons 2-16 code for a 677-amino acid POR protein (NCBI NP_000932.2). There is a single copy of 50 kb POR gene (NCBI NM_000941.2) in humans on chromosome 7 (7q11.23). Paralogs of POR include nitric oxide synthase (), NADPH:sulfite reductase (), and methionine synthase reductase (). Protein structure The 3D crystal structure of human POR has been determined.); The molecule is composed of four structural domains: the FMN-binding domain, the connecting domain, the FAD-binding domain, and NADPH-binding domain. The FMN-binding domain is similar to the structure of FMN-containing prot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adrenodoxin Reductase
Adrenodoxin reductase (Enzyme Nomenclature name: adrenodoxin-NADP+ reductase, EC 1.18.1.6), was first isolated from bovine adrenal cortex where it functions as the first enzyme in the mitochondrial P450 systems that catalyze essential steps in steroid hormone biosynthesis. Examination of complete genome sequences revealed that adrenodoxin reductase gene is present in most metazoans and prokaryotes. Nomenclature The name of the enzyme was coined based on its function to reduce a Fe-2S(2 iron, 2 sulfur) electron-transfer protein that was named adrenodoxin. Later, in some studies, the enzyme was also referred to as a "ferredoxin reductase", as adrenodoxin is a ferredoxin. In the human gene nomenclature, the standard name is ferredoxin reductase and the symbol is FDXR, with ADXR specified as a synonym. The assignment of the name "ferredoxin reductase" has been criticized as a misnomer because determination of the structure of adrenodoxin reductase revealed that it is completely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
D-amino Acid Oxidase
D-amino acid oxidase (DAAO; also OXDA or DAMOX) is an enzyme with the function on a molecular level to oxidize D-amino acids to the corresponding α-keto acids, producing ammonia and hydrogen peroxide. This results in a number of physiological effects in various systems, most notably the brain. The enzyme is most active toward neutral D-amino acids, and not active toward acidic D-amino acids. One of its most important targets in mammals is D-Serine in the central nervous system. By targeting this and other D-amino acids in vertebrates, DAAO is important in detoxification. The role in microorganisms is slightly different, breaking down D-amino acids to generate energy. DAAO is expressed in a wide range of species from yeasts to human. It is not present in plants or in bacteria which instead use D-amino acid dehydrogenase. DAAO in humans is a candidate susceptibility gene and together with G72 may play a role in the glutamatergic mechanisms of schizophrenia. DAAO also play ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spectroscopy
Spectroscopy is the field of study that measures and interprets electromagnetic spectra. In narrower contexts, spectroscopy is the precise study of color as generalized from visible light to all bands of the electromagnetic spectrum. Spectroscopy, primarily in the electromagnetic spectrum, is a fundamental exploratory tool in the fields of astronomy, chemistry, materials science, and physics, allowing the composition, physical structure and electronic structure of matter to be investigated at the atomic, molecular and macro scale, and over astronomical distances. Historically, spectroscopy originated as the study of the wavelength dependence of the absorption by gas phase matter of visible light dispersed by a prism. Current applications of spectroscopy include biomedical spectroscopy in the areas of tissue analysis and medical imaging. Matter waves and acoustic waves can also be considered forms of radiative energy, and recently gravitational waves have been associa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NADH
Nicotinamide adenine dinucleotide (NAD) is a coenzyme central to metabolism. Found in all living cells, NAD is called a dinucleotide because it consists of two nucleotides joined through their phosphate groups. One nucleotide contains an adenine nucleobase and the other, nicotinamide. NAD exists in two forms: an oxidized and reduced form, abbreviated as NAD and NADH (H for hydrogen), respectively. In cellular metabolism, NAD is involved in redox reactions, carrying electrons from one reaction to another, so it is found in two forms: NAD is an oxidizing agent, accepting electrons from other molecules and becoming reduced; with H+, this reaction forms NADH, which can be used as a reducing agent to donate electrons. These electron transfer reactions are the main function of NAD. It is also used in other cellular processes, most notably as a substrate of enzymes in adding or removing chemical groups to or from proteins, in posttranslational modifications. Because of the import ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxidation
Redox ( , , reduction–oxidation or oxidation–reduction) is a type of chemical reaction in which the oxidation states of the reactants change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a decrease in the oxidation state. The oxidation and reduction processes occur simultaneously in the chemical reaction. There are two classes of redox reactions: * Electron-transfer – Only one (usually) electron flows from the atom, ion, or molecule being oxidized to the atom, ion, or molecule that is reduced. This type of redox reaction is often discussed in terms of redox couples and electrode potentials. * Atom transfer – An atom transfers from one substrate to another. For example, in the rusting of iron, the oxidation state of iron atoms increases as the iron converts to an oxide, and simultaneously, the oxidation state of oxygen decreases as it accepts electrons released by the iron. Although oxidati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Apoenzyme
An enzyme () is a protein that acts as a biological catalyst 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 include catalytic RNA molecules, also called ribozymes. They are sometimes described as a ''type'' of enzyme rather than being ''like'' an enzyme, but even in the deca ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cellular Respiration
Cellular respiration is the process of oxidizing biological fuels using an inorganic electron acceptor, such as oxygen, to drive production of adenosine triphosphate (ATP), which stores chemical energy in a biologically accessible form. Cellular respiration may be described as a set of metabolic reactions and processes that take place in the cells of organisms to transfer chemical energy from nutrients to ATP, with the flow of electrons to an electron acceptor, and then release waste products. If the electron acceptor is oxygen, the process is more specifically known as aerobic cellular respiration. If the electron acceptor is a molecule other than oxygen, this is anaerobic cellular respiration. Fermentation, which is also an anaerobic process, is not respiration, as no external electron acceptor is involved. The reactions involved in respiration are catabolic reactions, which break large molecules into smaller ones, producing large amounts of energy (ATP). Respiration ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
