ALTERATION OF THE ACTIVITY AND SELECTIVITY OF IMMOBILIZED LIPASES BY THE EFFECT OF THE AMOUNT OF WATER IN THE ORGANIC MEDIUM

Lipase from Candida cylindracea has been covalently immobilized on agarose, silica and alumina. These enzymatic derivatives are inactive in synthesis after lyophilization (48 h) if an aqueous buffer is not added to the organic reaction medium. The addition of water restores the enzymatic activity of the immobilized lipase on agarose, but not on hydrophobic supports such as silica or alumina. Unlyophilized derivative on silica is more stable and active than the native enzyme in its optimum hydration conditions. In the esterification of racemic ibuprofen in isooctane, native and immobilized lipases are selective towards the S(+) enantiomer. Immobilized lipase on silica and native lipase have the same synthetic activity and selectivity, but the immobilized derivative is four times more stable at 25 degrees C than its soluble counterpart.