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Phosphorylase A
In biochemistry, phosphorylases are enzymes that catalyze the addition of a phosphate group from an inorganic phosphate (phosphate+hydrogen) to an acceptor. :A-B + P A + P-B They include allosteric enzymes that catalyze the production of glucose-1-phosphate from a glucan such as glycogen, starch or maltodextrin. Phosphorylase is also a common name used for glycogen phosphorylase in honor of Earl W. Sutherland Jr., who in the late 1930s discovered it as the first phosphorylase. Function Phosphorylases should not be confused with phosphatases, which remove phosphate groups. In more general terms, phosphorylases are enzymes that catalyze the addition of a phosphate group from an inorganic phosphate (phosphate + hydrogen) to an acceptor, not to be confused with a phosphatase (a hydrolase) or a kinase (a phosphotransferase). A phosphatase removes a phosphate group from a donor using water, whereas a kinase transfers a phosphate group from a donor (usually ATP) to an acceptor. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biochemistry
Biochemistry, or biological chemistry, is the study of chemical processes within and relating to living organisms. A sub-discipline of both chemistry and biology, biochemistry may be divided into three fields: structural biology, enzymology, and metabolism. Over the last decades of the 20th century, biochemistry has become successful at explaining living processes through these three disciplines. Almost all List of life sciences, areas of the life sciences are being uncovered and developed through biochemical methodology and research.#Voet, Voet (2005), p. 3. Biochemistry focuses on understanding the chemical basis that allows biomolecule, biological molecules to give rise to the processes that occur within living Cell (biology), cells and between cells,#Karp, Karp (2009), p. 2. in turn relating greatly to the understanding of tissue (biology), tissues and organ (anatomy), organs as well as organism structure and function.#Miller, Miller (2012). p. 62. Biochemistry is closely ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hydrolase
In biochemistry, hydrolases constitute a class of enzymes that commonly function as biochemical catalysts that use water to break a chemical bond: :\ce \quad \xrightarrowtext\quad \ce This typically results in dividing a larger molecule into smaller molecules. Some common examples of hydrolase enzymes are esterases including lipases, phosphatases, glycosidases, peptidases, and nucleosidases. Esterases cleave ester bonds in lipids and phosphatases cleave phosphate groups off molecules. An example of crucial esterase is acetylcholine esterase, which assists in transforming the neuron impulse into the acetate group after the hydrolase breaks the acetylcholine into choline and acetic acid. Acetic acid is an important metabolite in the body and a critical intermediate for other reactions such as glycolysis. Lipases hydrolyze glycerides. Glycosidases cleave sugar molecules off carbohydrates and peptidases hydrolyze peptide bonds. Nucleosidases hydrolyze the bonds of nucleo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycogen Storage Disease Type VI
Glycogen storage disease type VI (GSD VI) is a type of glycogen storage disease caused by a deficiency in liver glycogen phosphorylase or other components of the associated phosphorylase cascade system. It is also known as "Hers' disease", after Henri G. Hers, who characterized it in 1959. The scope of GSD VI now also includes glycogen storage disease type VIII, IX (caused by phosphorylase b kinase deficiency) and X (deficiency protein kinase A). The incidence of GSD VI is approximately 1 case per 65,000–85,000 births, representing approximately 30% all cases of glycogen storage disease. Signs and symptoms Patients generally have a benign course, and typically present with hepatomegaly and growth retardation early in childhood. Mild hypoglycemia, hyperlipidemia, and hyperketosis may occur. Lactic acid and uric acid Uric acid is a heterocyclic compound of carbon, nitrogen, oxygen, and hydrogen with the Chemical formula, formula C5H4N4O3. It forms ions and salts known a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glycogen Storage Disease Type V
Glycogen storage disease type V (GSD5, GSD-V), also known as McArdle's disease, is a metabolic disorder, one of the metabolic myopathies, more specifically a muscle glycogen storage disease, caused by a deficiency of myophosphorylase. Its incidence is reported as one in 100,000, roughly the same as glycogen storage disease type I. The disease was first reported in 1951 by British physician Brian McArdle of Guy's Hospital, London. Signs and symptoms Onset of symptoms and diagnostic delay In the classic phenotype, the onset of this disease is usually noticed in childhood, but often not diagnosed until the third or fourth decade of life, frequently due to misdiagnosis and dismissal of symptoms. The median age of symptom onset is 3 years, with the median diagnostic delay being 29 years. Misdiagnosis is overwhelmingly common, with approximately 90% of patients being misdiagnosed, and approximately 62% receiving multiple misdiagnoses before a correct diagnosis. The prolonged diagno ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Polynucleotide Phosphorylase
Polynucleotide Phosphorylase (PNPase) is a bifunctional enzyme with a phosphorolytic 3' to 5' exoribonuclease activity and a 3'-terminal oligonucleotide polymerase activity. That is, it dismantles the RNA chain starting at the 3' end and working toward the 5' end. It also synthesizes long, highly heteropolymeric tails ''in vivo''. It accounts for all of the observed residual polyadenylation in strains of ''Escherichia coli'' missing the normal polyadenylation enzyme. Discovered by Marianne Grunberg-Manago working in Severo Ochoa's lab in 1955, the RNA-polymerization activity of PNPase was initially believed to be responsible for DNA-dependent synthesis of messenger RNA, a notion that was disproven by the late 1950s. It is involved in mRNA processing and degradation in bacteria, plants, and animals. In humans, the enzyme is encoded by the gene. In its active form, the protein forms a ring structure consisting of three PNPase molecules. Each PNPase molecule consists of two R ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
RNase PH
RNase PH is a tRNA nucleotidyltransferase, present in archaea and bacteria, that is involved in tRNA processing. Contrary to hydrolytic enzymes, it is a phosphorolytic enzyme, meaning that it uses inorganic phosphate as a reactant to cleave nucleotide-nucleotide bonds, releasing diphosphate nucleotides. The active structure of the proteins is a homohexameric complex, consisting of three ribonuclease (RNase) PH dimers. RNase PH has homologues in many other organisms, which are referred to as RNase PH-like proteins. The part of another larger protein with a domain that is very similar to RNase PH is called an RNase PH domain (RPD). See also Two highly related exoribonuclease complexes: * Polynucleotide phosphorylase * Exosome complex The exosome complex (or PM/Scl complex, often just called the exosome) is a multi-protein intracellular complex capable of degrading various types of RNA (ribonucleic acid) molecules. Exosome complexes are found in both eukaryotic cells and a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Purine Nucleoside Phosphorylase
Purine nucleoside phosphorylase, PNP, PNPase or inosine phosphorylase () is an enzyme that in humans is encoded by the ''NP'' gene. It catalyzes the chemical reaction :purine nucleoside + phosphate \rightleftharpoons purine + alpha-D-ribose 1-phosphate Thus, the two substrates of this enzyme are a purine nucleoside and phosphate, whereas its products are a purine and alpha-D-ribose 1-phosphate. Nomenclature This enzyme belongs to the family of glycosyltransferases, specifically the pentosyltransferases. The systematic name of this enzyme class is purine-nucleoside:phosphate ribosyltransferase. Other names in common use include: * inosine phosphorylase * PNPase * PUNPI * PUNPII * inosine-guanosine phosphorylase * nucleotide phosphatase * purine deoxynucleoside phosphorylase * purine deoxyribonucleoside phosphorylase * purine nucleoside phosphorylase * purine ribonucleoside phosphorylas This enzyme participates in 3 metabolic pathways: purine metabolism, pyrimidine ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleoside
Nucleosides are glycosylamines that can be thought of as nucleotides without a phosphate group. A nucleoside consists simply of a nucleobase (also termed a nitrogenous base) and a five-carbon sugar (ribose or 2'-deoxyribose) whereas a nucleotide is composed of a nucleobase, a five-carbon sugar, and one or more phosphate groups. In a nucleoside, the anomeric carbon is linked through a glycosidic bond to the N9 of a purine or the N1 of a pyrimidine. Nucleotides are the molecular building blocks of DNA and RNA. List of nucleosides and corresponding nucleobases ''This list does not include modified nucleobases and the corresponding nucleosides'' Each chemical has a short symbol, useful when the chemical family is clear from the context, and a longer symbol, if further disambiguation is needed. For example, long nucleobase sequences in genomes are usually described by CATG symbols, not Cyt-Ade-Thy-Gua (see '' Nucleic acid sequence § Notation''). Sources Nucleosides can ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Maltodextrin Phosphorylase
Maltodextrin phosphorylase is a phosphorylase enzyme ( EC 2.4.1.1), more specifically one type of glycosyltransferase ( EC 2.4). Maltodextrin phosphorylase plays a critical role in maltodextrin metabolism in E. coli. This bacterial enzyme, often referred to as MalP, catalyzes the phosphorolysis of an α-1,4-glycosidic bond in maltodextrins, removing the non-reducing glucosyl residues of linear oligosaccharides as glucose-1-phosphate (Glc1P). Phosphorylases are well-regarded for their allosteric effects on metabolism, however MalP exhibits no allosteric properties. It has a higher affinity for linear oligosaccharides than the related glycogen phosphorylase. Mechanism Maltodextrin phosphorylase facilitates maltodextrin metabolism through phosphorolysis of nonreducing glucosyl residues in order to produce Glc1P. MalP has a higher affinity for short, linear α-1,4 linked glucose oligosaccharides, and consequently appears to act on maltodextrin degradation products. Without MalP, la ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Starch Phosphorylase
Starch phosphorylase is a form of phosphorylase similar to glycogen phosphorylase, except that it acts upon starch instead of glycogen Glycogen is a multibranched polysaccharide of glucose that serves as a form of energy storage in animals, fungi, and bacteria. It is the main storage form of glucose in the human body. Glycogen functions as one of three regularly used forms .... The plant alpha-glucan phosphorylase, commonly called starch phosphorylase (EC 2.4.1.1), is largely known for the phosphorolytic degradation of starch. Starch phosphorylase catalyzes the reversible transfer of glucosyl units from glucose-1-phosphate to the nonreducing end of alpha-1,4-D-glucan chains with the release of phosphate. Two distinct forms of starch phosphorylase, plastidic phosphorylase and cytosolic phosphorylase, have been consistently observed in higher plants. External links * * http://www.genome.ad.jp/dbget-bin/www_bget?ko+K00688 ** Rathore RS, Garg N, Garg S, Kumar A. Crit Rev Biot ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phosphonate
In organic chemistry, phosphonates or phosphonic acids are organophosphorus compounds containing Functional group, groups, where R is an organic group (alkyl, aryl). If R is hydrogen then the compound is a Phosphite_ester#Chemistry_of_HP(O)(OR)2, dialkyl phosphite, which is a different functional group. Phosphonic acids, typically handled as salts, are generally Volatility (chemistry), nonvolatile solids that are poorly soluble in organic solvents, but soluble in water and common Alcohol (chemistry), alcohols. Many commercially important compounds are phosphonates, including glyphosate (the active molecule of the herbicide Roundup (herbicide), Roundup), and ethephon, a widely used plant growth regulator. Bisphosphonates are popular drugs for treatment of osteoporosis.Svara, J.; Weferling, N.; Hofmann, T. "Phosphorus Compounds, Organic," in ''Ullmann's Encyclopedia of Industrial Chemistry'', Wiley-VCH, Weinheim, 2008. . In biochemistry and medicinal chemistry, phosphonate gr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Nucleotidyl
Nucleotidyltransferases are transferase enzymes of phosphorus-containing groups, e.g., substituents of nucleotidylic acids or simply nucleoside monophosphates. The general reaction of transferring a nucleoside monophosphate moiety from A to B, can be written as: :A-P-N + B \rightleftharpoons A + B-P-N For example, in the case of polymerases, A is pyrophosphate and B is the nascent polynucleotide. They are classified under EC number 2.7.7 and they can be categorised into: # Uridylyltransferases, which transfer uridylyl- groups # Adenylyltransferases, which transfer adenylyl- groups # Guanylyltransferases, which transfer guanylyl- groups # Cytitidylyltransferases, which transfer cytidylyl- groups # Thymidylyltransferases, which transfer thymidylyl- groups Role in metabolism Many metabolic enzymes are modified by nucleotidyltransferases. The attachment of an AMP (adenylylation) or UMP (uridylylation) can activate or inactivate an enzyme or change its specificity (see figure) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
