Influence of polyols on the stability and kinetic parameters of invertase from Candida utilis: correlation with the conformational stability and activity.

Invertase (beta-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 (T ( m )) rose from 75 degrees C to a maximum of 85 degrees C in 30% glycerol. The stabilization has been attributed to the preferential hydration of the enzyme.