Macromolecular crystallization procedure employing diffusion cells of varying depths as reservoirs to tailor the time course of equilibration in hanging- and sitting-drop vapor-diffusion and microdialysis experiments

A procedure and crystallization plate are described that allow control over the time course of equilibration between a macromolecule and a reservoir solution. The d² dependence of diffusion is exploited in a crystallization plate with reservoirs of varying depths to speed up or slow down the equilibration. A rationale is presented that suggests why this might be useful. The plate is a completely passive device, with no moving parts, that can be set up in about the same time as a traditional 24-well plate. It can, with equal facility, be used for hanging-drop or sitting-drop vapor diffusion or microdialysis crystallization experiments. The procedure has been used to grow very large diffraction-quality crystals of three protein-inhibitor complexes, one of which had failed to yield any but microcrystals by more traditional methods.