Influence of Polyols on the Stability and Kinetic Parameters of Invertase from Candida utilis: Correlation with the Conformational Stability and Activity

Invertase (b-D-fructofuranoside fructohydrolase-
E.C. 3.2.1.26) is a sucrose hydrolyzing enzyme found
in microbial, plant and animal sources. Invertase from
Candida utilis is a dimeric glycoprotein composed of two
identical monomer subunits with an apparent molecular
mass of 150 kDa. We investigated the mechanism of stabilization
of invertase with polyols (glycerol, xylitol, and
sorbitol). Activity, thermodynamic and kinetic measurements
of invertase were performed as a function of polyol
concentration and showed that polyols act as very effective
stabilizing agents. The result from the solvent-invertase
interaction shows preferential exclusion of the polyols
from the protein domain leading to preferential hydration
of protein. Apparent thermal denaturation temperature of
the protein (Tm) rose from 75 �C to a maximum of 85 �C in
30% glycerol. The stabilization has been attributed to the
preferential hydration of the enzyme.