EFFECT OF IMMISCIBLE ORGANIC-SOLVENTS ON ACTIVITY STABILITY OF NATIVE CHYMOTRYPSIN AND IMMOBILIZED-STABILIZED DERIVATIVES

We have developed different activity/stability tests to evaluate the possibilities of fully dispersed chymotrypsin derivatives as industrial catalysts in biphasic systems. We have tested different immiscible organic solvents (log P ranged from 0.65 to 2.8) and used different enzyme derivatives (soluble chymotrypsin and one-point and multipoint covalent attached derivatives). Special emphasis has been given to the role of the "exact composition of the aqueous phase." High phosphate concentrations largely protect every chymotrypsin derivative from the distorting effects of dissolved solvent molecules. The effects on the activity and stability of soluble chymotrypsin due to saturating solvent concentrations in an aqueous solution, and the much more severe effects of contact with the phase interface in a stirred biphasic system, all show the opposite trend for the influence of solvent polarity to that generally observed for biocatalysts. For example, deleterious effects decline in the order chloroform, dichloromethane, ethyl acetate. On the contrary, with or without stirring, our stabilized chymotrypsin-agarose derivatives are much more stable against these water-immiscible solvents, and their relative effects follow the normal trend. From these integrated activity and stability tests we can conclude that fully dispersed immobilized-stabilized derivatives seem to be an interesting alternative to develop industrial biphasic processes catalyzed by chymotrypsin.