Abstract
Physical (ionic exchange of ionic polymers) or chemical (aminoethylamidation, succinylation, hydroxyethylamidation) modifications of Novozym 435 have been performed and the resulting biocatalysts have been assayed in diverse reactions. The coating of the immobilized enzyme with dextran-sulphate
via ionic exchange permitted to increase the asymmetric factor of the biocatalyst from
A
=
13 (ee
=
83%) to 24 (ee
>
90%) in the hydrolysis of 3-phenylglutaric acid dimethyl diester, producing the (R)-monomethyl ester. The chemical succinylation of Novozym 435 permitted to enhance the biocatalyst enantiospecificity from
E
=
1 to 13 in the hydrolysis of (±)-mandelic acid methyl ester. In the hydrolysis of (±)-2-
O-butyryl-2-phenylacetic acid, the enantiospecificity of Novozym 435 was very high towards the S-enantiomer (
E
>
100) but it was inverted after the chemical hydroxyethylamidation of the immobilized enzyme (
E
=
6.6 towards R-enantiomer).
Thus, these simple protocols seem to be a very powerful tool to generate a library of biocatalysts from Novozym 435 with very different catalytic properties.