Partial purification and properties of ornithine carbamoyltransferase from Citrus limonum leaves.

Ornithine carbamoyltransferase (carbamoylphosphate: L-ornithine carbamoyltransferase, EC 2.1.3.3) has been partially purified from C.limonum leaves. The data indicate the presence of only the anabolic enzyme. The activity is strongly influenced by pH, ionic strength and ornithine concentration. Optimal activity for the enzyme dissolved in the tri-buffer: diethanolamine,2-(N-morpholino) ethanesulfonic acid, N-ethylenmorpholine (0.051 M/0.1 M/0.051 M) is at pH 9.0, when ornithine is 10 mM. The enzyme catalyses an ordered-sequential process in which carbamoyl phosphate binds first followed by L-ornithine and then L-citrulline leaves followed by phosphate. Support for this statement comes from product inhibition and evidence of abortive ternary complex formation.