A NOVEL TECHNIQUE TO CONTROL THE RATE OF VAPOR DIFFUSION, GIVING LARGER PROTEIN CRYSTALS

The process of protein crystallization often takes place tao rapidly, thus producing showers of crystals instead of large single crystals. A novel technique for improving protein-crystal size by slowing down th e crystallization process is described. This is achieved by the settin g up of a vapour-diffusion experiment with a layer of oil placed above the reservoir. The oil acts as a barrier between the reservoir and th e crystallization drop, but water vapour diffuses slowly through the l ayer of oil. The type of oil and the thickness of the oil layer situat ed above the reservoir will dictate the rate of vapour diffusion and c onsequently the speed of crystallization. This technique reduces the n umber of crystals grown and increases their size.