H2O + L-arginine = L-citrulline + NH4(+) Activated by Mg(2+) or Mn(2+) and strongly inhibited by Zn(2+). Amino-acid degradation; L-arginine degradation via ADI pathway; carbamoyl phosphate from L-arginine: step 1/2. Homodimer. Belongs to the arginine deiminase family.