Hydrolyzes ADP with high activity. Shows weak or no activity on 5'-AMP, 5'-GMP, 3'-AMP, ATP, cAMP, and cGMP. Is devoid of monophosphatase and proteinase activities. Dose-dependently inhibits platelet aggregation induced by ADP (IC(50)=0.99 uM) and collagen (IC(50)=1.4 uM). ADP + H2O = AMP + H(+) + phosphate Binds 2 divalent metal cations per subunit. Monomer cleaved in two subunits; disulfide-linked. Is synthesized as a single-chain protein and is subsequently cleaved to form a two-subunit protein held together with disulfide bonds. Expressed by venom gland. Belongs to the nucleotide pyrophosphatase/phosphodiesterase family.