The pathway of arginine catabolism in the parasitic flagellate Trichomonas vaginalis

Mol Biochem Parasitol. 1983 Jul;8(3):241-52. doi: 10.1016/0166-6851(83)90046-4.


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

  • Adenosine Diphosphate / pharmacology
  • Animals
  • Arginine / metabolism*
  • Carbon Dioxide / metabolism
  • Hydrolases / metabolism
  • Kinetics
  • Magnesium / pharmacology
  • Ornithine Carbamoyltransferase / metabolism
  • Phosphotransferases (Carboxyl Group Acceptor)*
  • Phosphotransferases / metabolism
  • Trichomonas vaginalis / metabolism*
  • Urease / metabolism


  • Carbon Dioxide
  • Adenosine Diphosphate
  • Arginine
  • Ornithine Carbamoyltransferase
  • Phosphotransferases
  • Phosphotransferases (Carboxyl Group Acceptor)
  • carbamate kinase
  • Hydrolases
  • Urease
  • arginine deiminase
  • Magnesium