title: The pathway of arginine catabolism in the parasitic flagellate Trichomonas vaginalis.
abstract: Arginine is rapidly depleted from the medium during the cultivation of T. vaginalis in a defined or semi-defined medium. It is broken down to ornithine, ammonia and carbon dioxide by the three enzymes of the dihydrolase pathway: arginine deiminase, catabolic ornithine carbamyltransferase (OCTase) and carbamate kinase. Arginase and urease as well as citrulline hydrolase appear to be absent. Ornithine, a product of the pathway was further converted to putrescine by an active ornithine decarboxylase. Apparent substrate Km values determined were arginine deiminase, 103 microM; catabolic OCTase, 71 microM; ornithine decarboxylase 134 microM. A substrate level phosphorylation is associated with the pathway; the significance of this to the overall energy economy of the cell is unclear.
mesh_terms: D000244:Adenosine Diphosphate / Q000494:pharmacology; D000818:Animals; D001120:Arginine / Q000378:metabolism*; D002245:Carbon Dioxide / Q000378:metabolism; D006867:Hydrolases / Q000378:metabolism; D007700:Kinetics; D008274:Magnesium / Q000494:pharmacology; D009954:Ornithine Carbamoyltransferase / Q000378:metabolism; D010770:Phosphotransferases / Q000378:metabolism; D017851:Phosphotransferases (Carboxyl Group Acceptor); D014246:Trichomonas vaginalis / Q000378:metabolism*; D014510:Urease / Q000378:metabolism
chemical_list: D002245:Carbon Dioxide; D000244:Adenosine Diphosphate; D001120:Arginine; D009954:Ornithine Carbamoyltransferase; D010770:Phosphotransferases; D017851:Phosphotransferases (Carboxyl Group Acceptor); C019288:carbamate kinase; D006867:Hydrolases; D014510:Urease; C019723:arginine deiminase; D008274:Magnesium