H2O + L-arginine = L-citrulline + NH4(+) Amino-acid degradation; L-arginine degradation via ADI pathway; carbamoyl phosphate from L-arginine: step 1/2. Belongs to the arginine deiminase family. There are two genes termed arcA in strain O6 of E.coli, one refers to an arginine deiminase and the other to a two-component regulator.