Purine nucleoside phosphorylase (PNP) is a purine-metabolizing enzyme that catalyzes the reversible phosphorolysis of 6-oxypurine (deoxy)nucleosides to their respective bases and (deoxy)ribose-1-phosphate. It is a key enzyme in the purine salvage pathway of mammalian cells. Purine nucleoside phosphorylase is a transferase that catalyzes the addition of phosphate and removal of a purine base from guanosine and similar nucleosides.PNP defects result in metabolic abnormalities and fatal T cell immunodeficiency. Purine nucleoside phosphorylase (PNP) is a target for leukemia, gout, and autoimmune disorders.
