Purification, crystallization and preliminary X-ray diffraction studies of disintegrin (schistatin) from saw-scaled viper (Echis carinatus)

This is the first report of crystallographic data on a disintegrin molecule from any source. The heterodimeric disintegrin with a molecular weight of 14 kDa from Echis carinatus venom is a potent antagonist of α4 integrins. The intact disintegrin, containing two subunits A and B, was isolated and purified using affinity and ion-exchange columns. It has been crystallized using 1.6 M ammonium sulfate as a precipitating agent. The crystals grew to dimensions of 0.25 × 0.20 × 0.20 mm and diffracted to 2.5 Å resolution. The crystals belong to space group I4₁22, with unit-cell parameters a = b = 91.7, c = 55.1 Å. Assuming a molecular weight of 14 kDa, a V_M of 2.1 ų Da⁻¹ is obtained for one molecule of disintegrin in the asymmetric unit.