Snake venom NAD nucleosidase: its occurrence in the venoms from the genus Agkistrodon and purification and properties of the enzyme from the venom of A. halys blomhoffii.

Abstract Nicotinamide adenine dinucleotide nucleosidase (NAD glycohydrolase, EC 3.2.2.5) was demonstrated in venoms of various snakes. Among the venoms from 37 species of Viperidae, Crotalidae and Elapidae, venom of snakes in the genera Bungarus and Agkistrodon showed the highest activities. No NAD nucleosidase activity was detected in venoms of the Naja genus. A NAD nucleosidase found in the venom of Agkistrodon halys blomhoffii was purified by successive column chromatographies on DEAE-cellulose and DEAE-Sephadex A-50 and gel-filtration on Sepharose 6B. Final purification was over 25-fold with 20 per cent yield. The purified enzyme showed maximal activity at pH 7.5 and hydrolysed β-NAD + , NADP + and 3-acetylpyridine adenine dinucleotide. No hydrolysis could be observed on α-NAD + , NADH, NADPH and NMN + . The Km values for β-NAD + , NADP + and 3-acetylpyridine adenine dinucleotide were 8.3 × 10 −4 M and 7.4 × 10 −4 M, respectively. Over 60 per cent inhibition of β-NAD + hydrolysis was observed in the presence of 10 −3 M of HgCl 2 and cysteine.