Involved in the catabolism of arginine. Catalyzes the phosphorolysis of citrulline, the reverse reaction of the biosynthetic one, yielding ornithine and carbamoyl phosphate which serve to generate ATP from ADP (PubMed:4962140, PubMed:2118516). This catabolic OTCase does not carry out the biosynthetic reaction because of a poor affinity and a marked cooperativity for carbamoyl phosphate (PubMed:2118516). carbamoyl phosphate + L-ornithine = H(+) + L-citrulline + phosphate Inhibited by 2-aminopentanoic acid (norvaline). Activated by phosphate and nucleoside monophosphates such as AMP, GMP, CMP, UMP. Allosterically inhibited by the polyamines such as spermidine and putrescine. Optimum pH is 7.3. Amino-acid degradation; L-arginine degradation via ADI pathway; carbamoyl phosphate from L-arginine: step 2/2. Nonameric or dodecamer (tetramer of trimers). During limiting aeration and in the presence of arginine. Cells lacking this gene are blocked in the arginine deiminase pathway. Proceeds by an ordered sequential mechanism with CP identified as the initial reactant. Belongs to the aspartate/ornithine carbamoyltransferase superfamily. OTCase family.