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Biliverdin Reductase
Biliverdin reductase (BVR) is an enzyme () found in all tissues under normal conditions, but especially in Mononuclear phagocyte system, reticulo-macrophages of the liver and spleen. BVR facilitates the conversion of biliverdin to bilirubin via the Organic redox reaction, reduction of a double bond between the second and third pyrrole ring into a single bond. There are two isozymes in humans, each encoded by its own gene, biliverdin reductase A (BLVRA) and biliverdin reductase B (BLVRB). Mechanism of catalysis BVR acts on biliverdin by reducing its double-bond between the pyrrole rings into a single-bond. It accomplishes this using NADPH + H+ as an electron donor, forming bilirubin and NADP+ as products. BVR catalyzes this reaction through an overlapping binding site including Lys18, Lys22, Lys179, Arg183, and Arg185 as key residues. This binding site attaches to biliverdin, and causes its dissociation from heme oxygenase (HO) (which catalyzes reaction of ferric heme --> b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biliverdin Reductase A
Biliverdin reductase A is a protein that in humans is encoded by the ''BLVRA'' gene. Function The protein encoded by this gene belongs to the biliverdin reductase family, members of which catalyze the conversion of biliverdin to bilirubin in the presence of NADPH or 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 ade .... Clinical significance Mutations in this gene are associated with hyperbiliverdinemia. References External links * PDBe-KBprovides an overview of all the structure information available in the PDB for Human Biliverdin reductase A EC 1.3.1 {{gene-7-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Rossmann Fold
The Rossmann fold is a tertiary fold found in proteins that bind nucleotides, such as enzyme cofactors FAD, NAD+, and NADP+. This fold is composed of alternating beta strands and alpha helical segments where the beta strands are hydrogen bonded to each other forming an extended beta sheet and the alpha helices surround both faces of the sheet to produce a three-layered sandwich. The classical Rossmann fold contains six beta strands whereas Rossmann-like folds, sometimes referred to as Rossmannoid folds, contain only five strands. The initial beta-alpha-beta (bab) fold is the most conserved segment of the Rossmann fold. The motif is named after Michael Rossmann who first noticed this structural motif in the enzyme lactate dehydrogenase in 1970 and who later observed that this was a frequently occurring motif in nucleotide binding proteins. Rossmann and Rossmannoid fold proteins are extremely common. They make up 20% of proteins with known structures in the Protein Data Bank, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glucuronic Acid
Glucuronic acid (GCA, from ) is a uronic acid that was first isolated from urine (hence the name "uronic acid"). It is found in many natural gum, gums such as gum arabic ( 18%), xanthan, and kombucha tea and is important for the metabolism of microorganisms, plants and animals. Properties Glucuronic acid is a sugar acid derived from glucose, with its sixth carbon atom oxidized to a carboxylic acid. In living beings, this primary oxidation occurs with Uridine diphosphate glucose, UDP-α-D-glucose (UDPG), not with the free sugar. Glucuronic acid, like its precursor glucose, can exist as a linear (carboxo-)aldohexose ( 60,000 are too large for renal excretion and will be excreted with bile into the intestine. Neonates are deficient in this conjugating system, making them particularly vulnerable to drugs such as chloramphenicol, which is inactivated by the addition of glucuronic acid, resulting in gray baby syndrome. Bilirubin is excreted in the bile as bilirubin diglucuronid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heme
Heme (American English), or haem (Commonwealth English, both pronounced /Help:IPA/English, hi:m/ ), is a ring-shaped iron-containing molecule that commonly serves as a Ligand (biochemistry), ligand of various proteins, more notably as a Prosthetic group, component of hemoglobin, which is necessary to bind oxygen in the bloodstream. It is composed of four pyrrole rings with 2 Vinyl group, vinyl and 2 propionic acid side chains. Heme is biosynthesized in both the bone marrow and the liver. Heme plays a critical role in multiple different redox reactions in mammals, due to its ability to carry the oxygen molecule. Reactions include oxidative metabolism (cytochrome c oxidase, succinate dehydrogenase), xenobiotic detoxification via cytochrome P450 pathways (including Drug metabolism, metabolism of some drugs), gas sensing (Guanylate cyclase, guanyl cyclases, nitric oxide synthase), and microRNA processing (DGCR8). Heme is a coordination complex "consisting of an iron ion coordinated ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Heme Oxygenase
Heme oxygenase, or haem oxygenase, (HMOX, commonly abbreviated as HO) is an enzyme that catalyzes the degradation of heme to produce biliverdin, ferrous iron, and carbon monoxide. There are many heme degrading enzymes in nature. In general, only aerobic heme degrading enzymes are referred to as HMOX-like enzymes whereas anaerobic enzymes are typically not affiliated with the HMOX family. Heme oxygenase Heme oxygenase (alternatively spelled using haem or oxidase) catalyzes the degradation of heme to biliverdin/bilirubin, ferrous ion, and carbon monoxide. The human genome may encode three isoforms of HMOX. The degradation of heme forms three distinct chromogens as seen in healing cycle of a bruise. This reaction can occur in virtually every cell and platelet; the classic example is the healing process of a contusion, which forms different chromogens as it gradually heals: (red) heme to (green) biliverdin to (yellow) bilirubin which is widely known for jaundice. In general, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reactive Oxygen Species
In chemistry and biology, reactive oxygen species (ROS) are highly Reactivity (chemistry), reactive chemicals formed from diatomic oxygen (), water, and hydrogen peroxide. Some prominent ROS are hydroperoxide (H2O2), superoxide (O2−), hydroxyl radical (OH.), and singlet oxygen(1O2). ROS are pervasive because they are readily produced from O2, which is abundant. ROS are important in many ways, both beneficial and otherwise. ROS function as signals, that turn on and off biological functions. They are intermediates in the redox behavior of O2, which is central to fuel cells. ROS are central to the photodegradation of organic pollutants in the atmosphere. Most often however, ROS are discussed in a biological context, ranging from their effects on aging and their role in causing dangerous genetic mutations. Inventory of ROS ROS are not uniformly defined. All sources include superoxide, singlet oxygen, and hydroxyl radical. Hydrogen peroxide is not nearly as reactive as these s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cofactor (biochemistry)
A cofactor is a non-protein chemical compound or metallic ion that is required for an enzyme's role as a catalyst (a catalyst is a substance that increases the rate of a chemical reaction). Cofactors can be considered "helper molecules" that assist in biochemical transformations. The rates at which these happen are characterized in an area of study called enzyme kinetics. Cofactors typically differ from ligands in that they often derive their function by remaining bound. Cofactors can be classified into two types: inorganic ions and complex organic molecules called coenzymes. Coenzymes are mostly derived from vitamins and other organic essential nutrients in small amounts. (Some scientists limit the use of the term "cofactor" for inorganic substances; both types are included here.) Coenzymes are further divided into two types. The first is called a " prosthetic group", which consists of a coenzyme that is tightly (or even covalently and, therefore, permanently) bound to a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Redox
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, 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 (chemistry), 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 r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Active Site
In biology and biochemistry, the active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction. The active site consists of amino acid residues that form temporary bonds with the substrate, the ''binding site'', and residues that catalyse a reaction of that substrate, the ''catalytic site''. Although the active site occupies only ~10–20% of the volume of an enzyme, it is the most important part as it directly catalyzes the chemical reaction. It usually consists of three to four amino acids, while other amino acids within the protein are required to maintain the tertiary structure of the enzymes. Each active site is evolved to be optimised to bind a particular substrate and catalyse a particular reaction, resulting in high specificity. This specificity is determined by the arrangement of amino acids within the active site and the structure of the substrates. Sometimes enzymes also need to bind with some cofactors to fulfil their functio ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biocatalysis
Biocatalysis refers to the use of living (biological) systems or their parts to speed up ( catalyze) chemical reactions. In biocatalytic processes, natural catalysts, such as enzymes, perform chemical transformations on organic compounds. Both enzymes that have been more or less isolated and enzymes still residing inside living cells are employed for this task. Modern biotechnology, specifically directed evolution, has made the production of modified or non-natural enzymes possible. This has enabled the development of enzymes that can catalyze novel small molecule transformations that may be difficult or impossible using classical synthetic organic chemistry. Utilizing natural or modified enzymes to perform organic synthesis is termed chemoenzymatic synthesis; the reactions performed by the enzyme are classified as chemoenzymatic reactions. History Biocatalysis underpins some of the oldest chemical transformations known to humans, for brewing predates recorded history. The old ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alpha Helix
An alpha helix (or α-helix) is a sequence of amino acids in a protein that are twisted into a coil (a helix). The alpha helix is the most common structural arrangement in the Protein secondary structure, secondary structure of proteins. It is also the most extreme type of local structure, and it is the local structure that is most easily predicted from a sequence of amino acids. The alpha helix has a right-handed helix conformation in which every backbone amino, N−H group hydrogen bonds to the backbone carbonyl, C=O group of the amino acid that is four residue (biochemistry), residues earlier in the protein sequence. Other names The alpha helix is also commonly called a: * Pauling–Corey–Branson α-helix (from the names of three scientists who described its structure) * 3.613-helix because there are 3.6 amino acids in one ring, with 13 atoms being involved in the ring formed by the hydrogen bond (starting with amidic hydrogen and ending with carbonyl oxygen) Discovery ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beta-sheet
The beta sheet (β-sheet, also β-pleated sheet) is a common structural motif, motif of the regular protein secondary structure. Beta sheets consist of beta strands (β-strands) connected laterally by at least two or three backbone chain, backbone hydrogen bonds, forming a generally twisted, pleated sheet. A β-strand is a stretch of peptide, polypeptide chain typically 3 to 10 amino acids long with backbone in an extended conformational isomerism, conformation. The supramolecular association of β-sheets has been implicated in the formation of the Amyloid fibril, fibrils and Amyloid plaques, protein aggregates observed in amyloidosis, Alzheimer's disease and other Proteinopathy, proteinopathies. History The first β-sheet structure was proposed by William Astbury in the 1930s. He proposed the idea of hydrogen bonding between the peptide bonds of parallel or antiparallel extended β-strands. However, Astbury did not have the necessary data on the bond geometry of the amino acids ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
