Pyridoxamine-5'-Phosphate Oxidase (PNPO)

Vitamin B6, or pyridoxal 5-prime-phosphate (PLP), is critical for normal cellular function, and some cancer cells have notable differences in vitamin B6 metabolism compared to their normal counterparts. The rate-limiting enzyme in vitamin B6 synthesis is pyridoxine-5-prime-phosphate (PNP) oxidase (PNPO; EC 1.4.3.5).

Pyridoxine 5’-phosphate oxidase is an enzyme that catalyzes several reactions in the vitamin B6 metabolism pathway. Pyridoxine-5-P oxidase catalyzes the terminal step (also the rate-limiting step) in vitamin B6 metabolism, the biosynthesis of pyridoxal-5’-phosphate, the biologically active form of vitamin B6 which acts as an essential cofactor.Pyridoxine 5’-phosphate oxidase is a member of the enzyme class oxidases, or more specifically, oxidoreductases.