Catalyzes the conversion of L-ornithine into L-proline with release of ammonia. Is likely involved in the L-ornithine degradation pathway that allows P.putida to utilize this compound as sole carbon and nitrogen source. L-ornithine = L-proline + NH4(+) Binds 1 NAD(+) pers subunit. Amino-acid biosynthesis; L-proline biosynthesis; L-proline from L-ornithine: step 1/1. Homodimer. Can be used for biotechnological production of L-proline when heterologously overexpressed in C.glutamicum. Belongs to the ornithine cyclodeaminase/mu-crystallin family.