Chymotrypsins modified by neutral or charged amphiphiles as catalysts for ester synthesis in polar organic solvents

αChymotrypsin has been modified by a series of neutral liposaccharidic or charged lipocarboxylic amphiphile reagents. In the esterification of N-acetyl tyrosine in three polar solvents, the new biocatalysts have been compared to chymotrypsins modified by reductive alkylation with glyoxylic acid, melibiose or octanal. This comparison indicates that the rate accelerations observed with the neutral or anionic amphiphile-coated enzymes are mainly due to the hydrophobization of the protein surface in the neigbourhood of the external lysine residues. This interpretation is strengthened by the favorable effect of supports more hydrophobic than celite on the reaction.