THERMOBAROSTABILITY OF ALPHA-CHYMOTRYPSIN IN REVERSED MICELLES OF AEROSOL OT IN OCTANE SOLVATED BY WATER-GLYCEROL MIXTURES

Thermostability of alpha-chymotrypsin at normal pressure in reversed m icelles depends on both an effective surfactant solvation degree and g lycerol content in the system. The difference in alpha-chymotrypsin st ability in reversed micelles at various glycerol concentrations [up to 60% (v/v)] was more pronounced at high surfactant degrees of solvatio n, R greater than or equal to 16. After a 1-h incubation at 40 degrees C in ''aqueous'' reversed micelles (in the absence of glycerol), alph a-chymotrypsin retained only 1% of initial catalytic activity and 10, 22, 59, and 48% residual activity in glycerol-solvated micelles with 2 0, 30, 50, and 60% (v/v) glycerol, respectively. The explanation of th e observed effects is given in the frames of micellar matrix structura l order increasing in the presence of glycerol as a water-miscible cos olvent that leads to the decreasing mobility of the alpha-chymotrypsin molecule and, thus the increase of its stability. It was found that g lycerol or hydrostatic pressure could be used to stabilize alpha-chymo trypsin in reversed micelles; a lower pressure is necessary to reach a given level of enzyme stability in the presence of glycerol. (C) 1998 John Wiley & Sons, Inc.