Ornithine cyclodeaminase

In enzymology, an ornithine cyclodeaminase (EC 4.3.1.12) is an enzyme that catalyzes the chemical reaction

Hence, this enzyme has one substrate, L-ornithine, and two products, L-proline and NH₄.

This enzyme belongs to the family of lyases, specifically ammonia lyases, which cleave carbon-nitrogen bonds. The systematic name of this enzyme class is L-ornithine ammonia-lyase (cyclizing; L-proline-forming). Other names in common use include ornithine cyclase, ornithine cyclase (deaminating), and L-ornithine ammonia-lyase (cyclizing). This enzyme participates in arginine and proline biosynthesis. It employs one cofactor, NAD+.