BIOCHEMICAL AND IMMUNOLOGICAL STUDIES ON PURINE NUCLEOSIDE PHOSPHORYLASE ISOLATED FROM COW SNOUT EPIDERMIS

Purine nucleoside phosphrylase (purine nucleoside : orthophospate ribosyl transferase PNPase, EC 2. 4. 2. 1) was purified 237-fold in a specific activity from cow snout epidermis. Inosine was highly utilized as substrate among the purine nucleosides tested. The molecular weight of the enzyme was estimated at about 80, 000 by the use of Sephadex G-200 gelfiltration. The Michaelis constant for inosine was 0.04 mM. There was no immunological cross-reactivity between antiserum of cow snout epidermal PNPase and calf spleen PNPase or extracts of cow liver, intestinal epitherium, kidney.