A cryocooling technique for protein crystals grown by dialysis from volatile solvents

The transfer of protein crystals from the original crystallization environm ent to cryoprotectants, heavy-atom solutions, or quartz capillary tubes, ex poses crystal droplets to conditions that can cause evaporation of the drop let and damage to the crystal. This problem is particularly acute for cryst als grown from volatile solvents or that are otherwise air-sensitive. Here a method that overcomes this problem is applied to crystals of macrophage i nflammatory protein II encoded by herpesvirus-8. The method is based on dia lysis and makes use of a dialysis adaptor that can be used with 24-well cry stallization plates. This method permits the transfer of crystals to cryopr otectant conditions with greater ease and lowers the risk of mechanical dam age relative to other available methods.