Enzymes involved in the production and catabolism of arginine. Arg1, arginase 1; Arg2, arginase 2; ASL, argininosuccinate lyase; ASS, argininosuccinate synthase; CPS, carbamoyl phosphate synthetase; eNOS, endothelial nitric oxide synthase; iNOS, inducible nitric oxide synthase; OAT, ornithine aminotransferase; OTC, ornithine transcarbamylase; P5CS, pyrroline 5-carboxylate synthase; PDG, phosphate-dependent glutaminase; POX, proline oxidase.