| arginine vasotocin | Vasotocin with arginyl residue at position 8 (identical with arginine oxytocin). See: arginine vasopressin. (05 Mar 2000) |
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| 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) |
| 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) |