Cryosolvents useful for protein and enzyme studies below-100 degrees C

For the study of protein structure, dynamics, and function, at very low tem peratures it is desirable to use cryosolvents that resist phase separation and crystallisation. We have examined these properties in a variety of cryo solvents. Using visual and X-ray diffraction criteria, methanol:ethanediol (70%:10%), methanol:glycerol (70%:10%), acetone:methoxy ethanol:ethanediol (35%:35%:10%), dimethylformamide:ethanediol (70%:10%), dimethylformamide (8 0%), methoxyethanol (80%), and methoxyethanol:ethanediol (70%:10%) were all found to be free of phase-changes down to at least - 160 degrees C. The le ast viscous of these, methanol:ethanediol (70%:10%), was miscible down to - 125 degrees C and showed no exo or endothermic transitions when examined u sing DSC. It is therefore potentially particularly suitable for very low te mperature cryoenzymology. (C) 2000 Elsevier Science BN: All rights reserved .