REMODELED ENZYME .2. ENZYMATIC FUNCTIONS OF FATTY ACID-MODIFIED CHYMOTRYPSIN AND TRYPSIN IN AQUEOUS-ORGANIC MEDIA

In our previous paper we demonstrated that chemical modification using the water-soluble acylating reagent, [p-hydroxy]phenyldimethylsulfonium methylsulfate, enabled us to introduce a variety of hydrophobic modifying groups into an enzyme molecule in an aqueous medium under mild conditions. To investigate the effects of these introducing groups on the hydrolytic activity of the modified enzyme, chymotrypsin and trypsin were modified with acetyl, decanoyl, lauroyl, myristoyl, and palmitoyl groups. We found an optimum carbon chain length and an optimum modification ratio for the fatty acid-modified enzyme to catalyze a hydrolytic reaction in aqueous-organic media, and the correlation between the hydrolytic activity and the dispersibility in the aqueous-organic media. Compared with the unmodified enzyme, the chemical modification reduced K(m), but had no significant effect on k(cat). The chemical modification seems to promote the dispersibility of the enzymes in aqueous-organic media, and leads to increasing the affinity of the enzyme to a substrate.