SOLUTION BEHAVIOR OF ALPHA-CHYMOTRYPSIN DISSOLVED IN NONPOLAR ORGANIC-SOLVENTS VIA HYDROPHOBIC ION-PAIRING

Dissolution of alpha-chymotrypsin in nonpolar organic solvents can be achieved using hydrophobic ion pairing, whereby the polar counterions ave replaced by a stoichiometric number of detergent molecules. Using Aerosol OT [AOT, sodium bis(2-octyl)sulfosuccinate], it is possible to partition significant amounts of the enzyme into alkanes and chloroca rbons. Apparent solubility in isooctane is greater than 1 mg/mL (80 mu M). Necessary conditions for achieving effective partitioning of alph a-chymotrypsin into these solvents are described. Using CD spectroscop y, it can be shown that the AOT-alpha-chymotrypsin (CMT) complex retai ns its native secondary and tertiary structure when dissolved in alkan es, and that the globular structure is stable to more than 100 degrees C. In contrast, alpha-chymotrypsin unfolds at 54 degrees C in aqueous solution. The relative solubility of the AOT-CMT complex in a variety of alkanes and chloracarbons is also reported. The native structure o f alpha-chymotrypsin is maintained in carbon tetrachloride, but not in methylene chloride or chloroform. (C) 1995 John Wiley & Sons, Inc.