| arginine-trna ligase | <enzyme> An enzyme that activates arginine with its specific transfer RNA. Chemical name: L-Arginine:tRNA(Arg)ligase (AMP-forming) Registry number: EC 6.1.1.19 (12 Dec 1998) |
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| argininosuccinase | <enzyme> An enzyme of the urea cycle which splits argininosuccinate to fumarate plus arginine. Its absence leads to the metabolic disease argininosuccinic acidemia in man. Chemical name: N-(L-Argininosuccinate) arginine-lyase Registry number: EC 4.3.2.1 (12 Dec 1998) |
| argininosuccinate lyase | <enzyme> An enzyme of the urea cycle which splits argininosuccinate to fumarate plus arginine. Its absence leads to the metabolic disease argininosuccinic acidemia in man. Chemical name: N-(L-Argininosuccinate) arginine-lyase Registry number: EC 4.3.2.1 (12 Dec 1998) |
| argininosuccinate synthase | <enzyme> An enzyme of the urea cycle that catalyses the formation of argininosuccinic acid from citrulline and aspartic acid in the presence of ATP. Absence or defect of this enzyme causes the metabolic disease citrullinaemia in man. Chemical name: L-Citrulline:L-aspartate ligase (AMP-forming) Registry number: EC 6.3.4.5 (12 Dec 1998) |
| argininosuccinic acid | <chemical> This amino acid is formed during the urea cycle from citrulline, aspartate and ATP. This reaction is catalyzed by argininosuccinic acid synthetase. Chemical name: L-Aspartic acid, N-(((4-amino-4-carboxybutyl)amino)iminomethyl)-, (S)- (12 Dec 1998) |
| argininosuccinic aciduria | <biochemistry> Argininosuccinic aciduria, an autosomal recessive defect of the urea cycle, is due to deficiency of argininosuccinate lyase (argininosuccinase), which catalyses the hydrolysis of argininosuccinic acid to arginine and fumaric acid. It is characterised by excessive urinary excretion of argininosuccinic acid, epilepsy, ataxia, mental retardation, liver disease, and friable, tufted hair; presumed to be the consequence of a deficiency of an enzyme responsible for splitting argininosuccinic acid to arginine and fumaric acid. Argininosuccinase is a cytosolic enzyme found in highest amounts in the liver. Like the other urea cycle defects except for arginase deficiency, argininosuccinic aciduria typically presents early in the neonatal period with serious, often fatal, hyperammonaemia and residual neurologic damage. Argininosuccinic acid is found in high concentrations in plasma and urine by amino acid chromatography. It can also be detected in amniotic fluid for purposes of prenatal diagnosis. Diagnosis is confirmed by specific enzyme assay. The argininosuccinase gene has been cloned and is found on chromosome 7. Inheritance: autosomal recessive. Acronym: ASA (05 Mar 2000) |
| arginyl | The aminoacyl radical of arginine. (05 Mar 2000) |
| arginyllysine esteropeptidase | <enzyme> Cleaves peptides at arg-lys bond; converts somatostatin 28 into somatostatin 14 Registry number: EC 3.4.22.- Synonym: arg-lys esteropeptidase, arginyl-lysyl-esteropeptidase (26 Jun 1999) |
| argipressin | <chemical> Cys-tyr-phe-gln-asn-cys-pro-arg-gly-nh2, cyclic 1-6 disulfide. The usual mammalian antidiuretic hormone, it is a cyclic nonapeptide with arginine in position 8 of the chain. Argipressin is used to treat diabetes insipidus and as haemostatic because of its vasoconstrictor action. Pharmacological action: haemostatics, renal agents, vasoconstrictor agents. Chemical name: Vasopressin, 8-L-arginine- (12 Dec 1998) |
| argive | Of or performance to Argos, the capital of Argolis in Greece. A native of Argos. Often used as a generic term, equivalent to Grecian or Greek. Origin: L. Argivus, fr. Argos, Argi. Source: Websters Dictionary (01 Mar 1998) |
| argo | 1. The name of the ship which carried Jason and his fifty-four companions to Colchis, in quest of the Golden Fleece. 2. <astronomy> A large constellation in the southern hemisphere, called also Argo Navis. In modern astronomy it is replaced by its three divisions, Carina, Puppis, and Vela. Origin: L. Argo, Gr. Source: Websters Dictionary (01 Mar 1998) |
| argol | Crude tartar; an acidulous salt from which cream of tartar is prepared. It exists in the juice of grapes, and is deposited from wines on the sides of the casks. Origin: Cf. Argal, Orgal. Of unknown origin. Source: Websters Dictionary (01 Mar 1998) |
| argon | <chemistry, element> A substance regarded as an element, contained in the atmosphere and remarkable for its chemical inertness. Origin: Gr. Inactive. Source: Websters Dictionary (01 Mar 1998) |
| argonaut | 1. Any one of the legendary Greek heroes who sailed with Jason, in the Argo, in quest of the Golden Fleece. 2. <zoology> A cephalopod of the genus Argonauta. Origin: L. Argonauta, Gr.; + sailor, ship. See Argo. Source: Websters Dictionary (01 Mar 1998) |
| argonauta | <zoology> A genus of Cephalopoda. The shell is called paper nautilus or paper sailor. The animal has much resemblance to an Octopus. It has eight arms, two of which are expanded at the end and clasp the shell, but are never elevated in the air for sails as was formerly supposed. The creature swims beneath the surface by means of a jet of water, like other cephalopods. The male has no shell, and is much smaller than the female. See Hectocotylus. Source: Websters Dictionary (01 Mar 1998) |