| phosphoryl | 1. <chemistry> The radical PO, regarded as the typical nucleus of certain compounds. 2. <prefix> Prefix incorrectly used to signify a phosphate (e.g., phosphorylcholine) in place of the correct O-phosphono-or phospho-. Source: Websters Dictionary (21 Jun 2000) |
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| phosphorylase | <enzyme> Enzyme that catalyses the sequential removal of glycosyl residues from glycogen to yield one glucose-1-phosphate per reaction. Its activity is controlled by phosphorylation (by phosphorylase kinase). (21 Jun 2000) |
| phosphorylase a | <enzyme> The phosphorylated and more active form of phosphorylase that functions as a regulatory enzyme during glycogen breakdown. The phosphate groups are hydrolytically removed by phosphorylase phosphatase to form phosphorylase b and orthophosphate. Registry number: EC 2.4.1.- (12 Dec 1998) |
| phosphorylase b | <enzyme> The relatively inactive form of phosphorylase that is reactivated to form phosphorylase a by phosphorylase kinase, which catalyses the enzymatic phosphorylation of the serine residues at the expense of ATP. Registry number: EC 2.4.1.- (12 Dec 1998) |
| phosphorylase kinase | <enzyme> The enzyme that regulates the activity of phosphorylase and glycogen synthetase by addition of phosphate groups. A large and complex enzyme, itself regulated by phosphorylation. Integrates the hormonal and calcium signals in muscle. (18 Nov 1997) |
| phosphorylase kinase phosphatase | <enzyme> Aspect of phosphoprotein phosphatase EC 3.1.3.16 Registry number: EC 3.1.3.- (26 Jun 1999) |
| phosphorylase phosphatase | <enzyme> An enzyme that deactivates glycogen phosphorylase a by releasing inorganic phosphate and phosphorylase b, the inactive form. Chemical name: (Phosphorylase a) phosphohydrolase Registry number: EC 3.1.3.17 (12 Dec 1998) |
| phosphorylase-rupturing enzyme | <enzyme> An enzyme that deactivates glycogen phosphorylase a by releasing inorganic phosphate and phosphorylase b, the inactive form. Chemical name: (Phosphorylase a) phosphohydrolase Registry number: EC 3.1.3.17 (12 Dec 1998) |
| phosphorylases | 1. General term for enzymes transferring an inorganic phosphate group to some organic acceptor, hence belonging to the transferases. 2. Specifically, enzymes that release a single glucosyl residue from a polyglucose as d-glucose 1-phosphate, the phosphate coming from inorganic orthophosphate; e.g., phosphophorylase, sucrose phosphorylases, cellobiose phosphorylases. (05 Mar 2000) |
| phosphorylation | <biochemistry> The creation of a phosphate derivative of an organic molecule. This isusually achieved by transferring a phosphate group from ATP. (09 Oct 1997) |
| phosphorylation of proteins | <biochemistry> Addition of phosphate groups to hydroxyl groups on proteins (side chains s, T or Y) catalysed by a protein kinase often specific) with ATP as phosphate donor. Activity of proteins is often regulated by phosphorylation. (18 Nov 1997) |
| phosphorylcholine | <chemical> (2-hydroxyethyl)trimethylammonium chloride phosphate. Calcium and magnesium salts used therapeutically in hepatobiliary dysfunction. Chemical name: Ethanaminium, N,N,N-trimethyl-2-(phosphonooxy)-, chloride (12 Dec 1998) |
| phosphorylethanolamine glyceridetransferase | <enzyme> An enzyme that catalyses reversibly the transfer of phosphoethanolamine from cdp-ethanolamine to diacylglycerol to yield phosphatidylethanolamine (cephalin) and cmp. The enzyme is found in the endoplasmic reticulum. Chemical name: CDPethanolamine:1,2-diacylglycerol ethanolaminephosphotransferase Registry number: EC 2.7.8.1 (12 Dec 1998) |
| phosphorylphosphatase | <enzyme> May be reversed to catalyze the in vitro synthesis of sarin and soman from their corresponding hydrolytic products Registry number: EC 3.1.3.- Synonym: organophosphate hydrolase (26 Jun 1999) |