Antitumor protein. Has a powerful and dose-dependent inhibitory effect on antigen, superantigen, or mitogen-stimulated human peripheral blood mononuclear cell (PBMC) proliferation. It may inhibit cell proliferation by arresting cell cycle and inducing apoptosis. H2O + L-arginine = L-citrulline + NH4(+) Amino-acid degradation; L-arginine degradation via ADI pathway; carbamoyl phosphate from L-arginine: step 1/2. Homodimer. Glycosylated. Belongs to the arginine deiminase family.