Micro diffusion cells for the growth of single protein crystals by means of equilibrium dialysis

Microdiffusion cells are described for crystallization of small volumes of protein solutions by equilibrium dialysis against a precipitant. The cells which may contain down to 10 microliters of protein solution are made either from capillaries of glass or transparent polymer sealed with cellophane membranes or from X-ray capillaries sealed with semipermeable diaphragms of polyacrylamide. The use of these microdiffusion cells has been explored both for growing large protein crystals and for chemical treatment of one or a few single crystals in their mother liquor. The methods have been applied to lysozyme, an extracellular proteinase from a strain of Arthrobacter and to rabbit muscle aldolase. The factors influencing the growth of protein crystals are discussed and other methods for protein crystallization are briefly reviewed.