Methods for separating nucleation and growth in protein crystallisation

The availability of high-quality crystals is crucial to the structure determination of proteins by X-ray diffraction. With the advent of structural genomics the pressure to produce crystals is greater than ever before. Finding favourable conditions for crystallisation is usually achieved by screening of the protein solution with numerous crystallising agents. Optimisation of the crystallisation conditions involves the manipulation of the crystallisation phase diagram with the aim of leading crystal growth in the direction that will produce the desired results. This article highlights recent advances in experimental methods for improving crystal size and quality by separating the nucleation and growth phases of crystallisation using the vapour diffusion and microbatch techniques.