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.