Crystallization and preliminary diffraction data of a platelet‐aggregation inhibitor from the venom of Agkistrodon piscivorus piscivorus (North American water moccasin)

Applaggin ( Agkistrodon piscivorus piscivorus platelet‐aggregation inhibitor) is a potent inhibitor of blood platelet aggregation derived from the venom of the North American water moccasin. The protein consists of 71 amino acids, is rich in cysteines, contains the sequence‐recognition site of adhesion proteins at positions 50–52 (Arg‐Gly‐Asp) and shares high sequence homology with other snake‐venom disintegrins such as echistatin, kistrin and trigramin. Single crystals of applaggin have been grown and X‐ray diffraction data have been collected to a resolution of 3.2 Å. The crystals belong to space group P 4 1 2 1 2 (or its enantiomorph), with unit‐cell dimensions a  =  b  = 63.35, c = 74.18 Å and two molecules per asymmetric unit. Molecular replacement using models constructed from the NMR structures of echistatin and kistrin has not been successful in producing a trial structure for applaggin.