STRUCTURAL AND CATALYTIC PROPERTIES OF ENZYMES IN REVERSE MICELLES

Structural and catalytic properties of two enzymes-alpha-chymotrypsin and horse liver alcohol dehydrogenase (LADH)-are studied in bis(2-ethy lhexyl) sodium sulfosuccinate (AOT)-isooctane reverse-micelle solution s. Circular dichroism (CD) and electron paramagnetic resonance spectro scopy (EPR) studies show little change in alpha-chymotrypsin structure upon incorporation into reverse micelles. For LADH, large perturbatio ns in structure are seen upon solubilization in reverse micelles. Thes e structural properties explain, in part, the observed activity of the se two enzymes in reverse micelles. Alpha-Chymotrypsin retains activit y in reverse micelles and, in some cases, displays enhanced activity. A sixfold increase in the turnover number was observed in w0 = 10 reve rse micelles. LADH has low activity in reverse micelles compared to th at in aqueous solution. At w0 = 70, the turnover number of LADH is 18% of the aqueous value. Active-site titrations show a decrease in activ e enzyme concentration for both enzymes upon incorporation into revers e micelles. Little change in the structure of both LADH and alpha-chym otrypsin is observed with change of water content in the reverse-micel le system.