APPLICATION OF OSMOTIC DEWATERING TO THE CONTROLLED CRYSTALLIZATION OF BIOLOGICAL MACROMOLECULES AND ORGANIC-COMPOUNDS

Several methods of crystallization of biological macromolecules depend upon the transport of water through the vapor phase - a process that is sensitive to ambient conditions (temperature, relative humidity). Other methods depend on the transport of solute by diffusion or through a membrane. By regulating the solute concentration on the outside of a reverse-osmosis membrane it is possible to control the rate at which macromolecules and other solutes are concentrated inside a membrane-bound fluid. The effect of dewatering rate on lysozyme crystal quality and growth rate was assessed. A 3-fold increase in concentration over a 9 day period yielded tetragonal crystals 0.5 mm on a side with sharp edges and with ordering at least to 1.73 angstrom. Transparent crystals of triglycine sulfate were grown by osmotic dewatering; in this case crystal growth could be enhanced or reversed by manipulating the external solution.