| phosphoamidase | <enzyme> An enzyme catalyzing the hydrolysis of phosphorus-nitrogen bonds, notably the hydrolysis of N-phosphocreatine to creatine and orthophosphate. Synonym: phosphamidase. (05 Mar 2000) |
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| phosphoamides | Amides of phosphoric acid (phosphoramidic acids) and their salts or esters (phosphoramidates), of the general formula (HO)2P(O)-NH2; e.g., creatine phosphate. (05 Mar 2000) |
| phosphoamino acids | Amino acids that contain phosphorus as an integral part of the molecule. (12 Dec 1998) |
| phosphoarginine | A compound (in particular, a phosphagen) of l-arginine with phosphoric acid containing the phosphoamide bond; a source of energy in the contraction of muscle in invertebrates, corresponding to phosphocreatine in the muscles of vertebrates. Compare: phosphocreatine. Synonym: arginine phosphate. (05 Mar 2000) |
| phosphocellobiase | <enzyme> Cellobiose monophosphate and water gives glucose and glucose-6-p Registry number: EC 3.2.1.- (26 Jun 1999) |
| phosphocholine | (CH3)3N+-CH2 CH2-OPO3 H-; choline O-phosphate;important in choline metabolism, e.g., as in cytidinediphosphocholine and in the biosynthesis of lecithins. Synonym: O-phosphocholine, phosphorylcholine. Phosphocholine cytidylyltransferase, an enzyme that catalyses the reaction of phosphocholine with CTP to form pyrophosphate and CDP-choline; the rate-limiting step of lecithin biosynthesis; the cytosolic form of the enzyme is inactive (a phosphorylated form of the enzyme). Phosphocholine diacylglycerol transferase, an enzyme in lecithin biosynthesis that catalyses the reaction of 1,2-diacylglycerol with CDP-choline to form CMP and phosphatidylcholine. (05 Mar 2000) |
| phosphocholine phosphatase | <enzyme> Unlike alkaline phosphatase the hamster heart enzyme has a different pH optimum and heat sensitivity and is not inhibited by amino acids Registry number: EC 3.1.3.- (26 Jun 1999) |
| phosphocreatine | <biochemistry> Present in high concentration (about 20mM) in striated muscle and is synthesised and broken down by creatine phosphokinase to buffer ATP concentration. It acts as an immediate energy reserve for muscle. (18 Nov 1997) |
| phosphodiester | A diesterified orthophosphoric acid, RO-(PO2H)-OR', as in the nucleic acids. (05 Mar 2000) |
| phosphodiester bond | <chemistry> Not a precise term. Refers to any molecule in which two parts are joined through a phosphate group. Examples are found in RNA, DNA, phospholipids, cyclic nucleotides, nucleotide diphosphates and triphosphates. (18 Nov 1997) |
| phosphodiester hydrolases | Enzymes (EC sub-subclass 3.1.4) cleaving phosphodiester bonds, such as those in cAMP or between nucleotides in nucleic acids, liberating smaller poly-or oligonucleotide units or mononucleotides but not inorganic phosphate. Synonym: phosphodiester hydrolases. (05 Mar 2000) |
| phosphodiester linkage | <biochemistry> A chemical linkage in which two alcohols are esterically boundto a bridging molecule of phosphoric acid. (31 Dec 1997) |
| phosphodiesterase | <enzyme> An enzyme that cleaves phosphodiesters to give a phosphomonoester and a free hydroxyl group. Examples include RNase, DNase, phospholipases C and D and the enzymes that convert cyclic nucleotides to the monoester forms. In casual usage the cAMP phosphodiesterase is usually meant. (18 Nov 1997) |
| phosphodiesterase inhibitors | Compounds which inhibit or antagonise the biosynthesis or actions of phosphodiesterases. (12 Dec 1998) |
| phosphodiesterase-phosphomonoesterase | <enzyme> From fusarium moniliforme; hydrolyzes both phosphodiesters and phosphomonoesters Registry number: EC 3.1.- Synonym: pdmase (26 Jun 1999) |