Ornithine carbamoyltransferase

Aletor, V.A. and B.L. Fetuga. 1988. The interactive effects of lima bean (Phaseolus lunatus) trypsin inhibitor, hemagglutinin and cyanide on some hepatic dehydrogenases, ornithine carbamoyltransferase and intestinal disaccharidases in weanling rats. Veterin. Human Toxicol. 30 540-544. 

This enzyme [EC 3.5.3.12], also known as agmatine imi-nohydrolase, catalyzes the hydrolysis of agmatine to produce A/ -carbamoylputrescine and ammonia. The plant enzyme also catalyzes the reactions of EC 2.1.3.3 (ornithine carbamoyltransferase), EC 2.1.3.6 (putrescine car-bamoyltransferase) and EC 2.122 (carbamate kinase), thereby functioning as a putrescine synthase, converting agmatine and ornithine into putrescine and citrulline, respectively. 

This enzyme [EC 2.1.3.6] catalyzes the reaction of carbamoyl phosphate with putrescine to produce orthophosphate and A-carbamoylputrescine. The plant enzyme will also catalyze the reactions of ornithine carbamoyltransferase, carbamate kinase, and agmatine deimmase. 

ORNITHINE TRANSCARBAMOYLASE d-ORNITHINE 4,5-AMINOMUTASE ORNITHINE AMINOTRANSFERASE ORNITHINE DECARBOXYLASE Ornithine carbamoyltransferase,... 

Ornithine carbamoyltransferase deficiency p Glnf, Citf, Alaj, Lysj, ArgJ,... 

Table 2.1.9 Changes of blood amino acids in various primary inherited defects and as a result of secondary changes. ASA Argininosuccinic acid, CPS carbamoyl phosphate synthase, LPI Lysinuric protein intolerance, MAD multiple acyl-CoA dehydrogenation, MSUD maple syrup urine disease, NAGS N-acetylglutamate synthase, NKH nonketotic hyperglycinemia, NTBC 2-(2-nitro-4-3 trifluoro-methylbenzoyl)-1,3-cyclohexanedione, OCT Ornithine carbamoyltransferase,...

Kay JD, Hilton-Jones D, Hyman N. Valproate toxicity and ornithine carbamoyltransferase deficiency. Lancet 1986 2(8518) 1283 1. 

ATCase and ornithine carbamoyltransferase (OTCase) catalyze analogous reactions. ATCase transfers the carbamoyl moiety from carbamoyl phosphate to aspartate, and OTCase transfers the carbamoyl moiety from carbamoyl phosphate to ornithine. They both share a common N-terminal functional domain, which binds carbamoyl phosphate. The C-terminal domains of these enzymes are structurally similar but have... 

Andersson SG, Karlberg 0, Canback B, Kurland CG (2003b) On the origin of mitochondria a genomics perspective. Philos Trans R Soc Lond B Biol Sci 358 165-179 Arakawa H, Amaya Y, Mori M (1990) The NH2-terminal 14-16 amino acids of mitochondrial and bacterial thiolases can direct mature ornithine carbamoyltransferase into mitochondria. J Biochem (Tokyo) 107 160-164... 

The first reaction of the urea cycle takes place in the matrix of the mitochondria and is catalyzed by ornithine carbamoyltransferase. 

As a congenital disorder, an enzyme deficiency in the urea cycle relates to carbamoylphosphate synthetase or N-ace-tyl-glutamate synthetase (= hyperammonaemia type I) and ornithine carbamoyltransferase (= hyperammonaemia type II) (D.B. Flannery et al., 1982). (27) (s. p. 594) This condition mainly affects the channelling of ammonium into the mitochondria and the conversion of ornithine into citrulline. (s. fig. 3.12) Similar acquired enzymopathies can be expected in Reye s syndrome and in cases of zinc deficiency. Such a hyperammonaemia syndrome can also produce the clinical picture of HE. 

Ornithine carbamoyltransferase Oral glucose tolerance test Overlap syndrome Orthotopic liver transplantation Open reading frame... 

Xp21.1 68.97 OTC Ornithine carbamoyltransferase 300461 Ornithine transcarbamylase deficiency, Duchenne muscular dystrophy... 

Formation of urea in hepatocytes. NAGS = N-acetylglutamate synthase CPSI = carbamoylphosphate synthase I OCT = ornithine carbamoyltransferase C-OT = citrulline-omithine translocase AS = argininosuccinate synthase AL = argininosuccinate lyase A = arginase. — -> indicates the absolute requirement of N-acetylglutamate for CPSI activity. 

Ornithine carbamoyltransferase (ornithine transcar-bamoylase) catalyzes the condensation between carbamoyl phosphate and ornithine to yield citrulline in mitochondria ... 

The catabolism of amino acids results in the release of nitrogen. Many parasites excrete the excess nitrogen in the form of ammonia. In protozoa there is no evidence for a complete urea cycle which would allow the conversion of ammonia into urea, and urea released by some species (49,50) is likely to be formed solely as a product of arginine catabolism. Urea makes up between 2 and 10% of the total nitrogenous end-product of helminths, but evidence for a functional urea cycle in parasitic species has been equivocal (1). Arginase and ornithine carbamoyltransferase do occur widely but the other urea cycle enzymes do not. Small quantities of uric acid are excreted by some cestodes and trematodes. 

Ishikawa, H., T. Matsuzawa, K. Ohashi, and Y. Nagamura. 2003. A novel method of measuring serum ornithine carbamoyltransferase. Annals of Clinical Biochemistry 40 264—268. 

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