Arginase EC

Arginase (EC 3.5.3.T) mediates the hydrolytic cleavage of L-canavanine to produce L-canaline and urea. L-Canaline, 2-amino-4-aminooxybutyric acid, bears the same structural analogy to L-ornithine as canavanine does to arginine. The aminooxy group of canaline with its pK value of 3.96 differs markedly from the 6-amino function of ornithine (pK = 10.76). 

The attachment of carbohydrate to proteins has also been used as a means of prolonging the survival of proteins in the circulation. The attachment of dextran to alpha amylase, catalase7 (EC 1.11.1.6), arginase (EC 3.5.3.1), and carboxypeptidase G (EC 3.4.12.10)158 prolonged their serum half-lives in rats and mice. The attachment of dextran presumably diminished the susceptibility of the conjugates to proteolysis, uptake by the reticuloendothelial system, and filtration by the kidney. The immunogenicity of alpha amylase and catalase was also considerably lessened, although not entirely eliminated.7... 

Biosynthesis metabolism C. is probably formed by reactions similar to the urea cycle and cleaved by arginase (EC 3.5.3.1) to canaline (0-amino-L-ho-moserine) and urea. Canaline can convert to L-homo-serine. 

Arg is a glucogenic amino acid, and it is semi-essential for humans, rats and chicks, i.e. it is not required by the adults of these species, but the young animals are unable to synthesize it rapidly enough to satisfy their total needs for growth and development. Arg is synthesized in the Urea cycle (see) where it serves as an important intermediate. It is attacked by various enzymes, depending on the species 1. arginase (EC 3.5.3.1) hydrolyses Arg that is released pro-... 

The incubation of resident peritoneal macrophages with bacterial lipopolysaccharide induced high arginase (EC 3.5.3.1) activity as judged by the consumption of C (U)-L-arginine and the release of labelled ornithine into the cell supernatant (Kriegbaum and Droge 1985). 

Another case in point is l-canavanine (11.75), a natural oximine that exhibits antitumor activity. When administered orally or parenterally to rats, most of the dose is recovered in the urine, and practically no unchanged compound is found [110]. The predominant route of metabolism by far is C=N bond cleavage to yield urea (11.76) and L-canaline (11.77), a reaction believed to be catalyzed by arginase (arginine amidinase, EC 3.5.3.1). 

Examples of typical enzyme names are arginase, which acts on arginine, and urease, which acts on urea (Chap. 15). Two atypical common names are pepsin, a digestive tract proteolytic enzyme (EC number 3.4.23.1), and, more exotically, rhodanese (thiosulfate cyanide sulfurtransferase, EC 2.8.1.1), which is in mammalian liver and kidney and catalyzes the removal of cyanide and thiosulfate from the body. In the latter case, it is understandable why the old name has remained in common use. 

The official EC name of this enzyme is L-arginine amidinohydrolase, the last word refers to the fact that the amidino group (dotted circle in the equation) is cleaved from arginine by introduction of a molecule of water across the C—N bond. In the reaction, a nonpeptide C—N bond is cleaved thus, the second EC number for arginase is 5 its whole classification number is 3.5.3.1. 

Carboxypeptidase N (EC 3.4.17.3 kininase I arginase carboxypeptidase) is a zinc-metalloproteinase. Notable substrates of this soluble enzyme include bradykinin (to form [desArg ]-BK, active at B, bradykinin receptors), enkephalins and atrial natriuretic peptide. An inhibitor used is MERGETPA. but it is not very selective. 

Carl GF, Blackwell LK, Barnett EC, et al. 1993. Manganese and epilepsy Brain glutamine synthetase and liver arginase activities in genetically epilepsy prone and chronically seizured rats. Epilepsia 34 441-446. 

Braissant 0, Gotoh T, Loup M, Mori M, Bachmann C. L-arginine uptake, the citrul-line-NO-cycle and arginase II in the rat brain an in situ hybridisation study. Mo/ec-ular Brain Research 1999 70(2) 231-241. 

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