STABILITY OF HYDROPHOBIC LIPASE DERIVATIVES IMMOBILIZED ON ORGANIC POLYMER BEADS

Lipase from Candida rugosa was immobilized by attaching various hydrop hobic groups to the enzyme molecule and adsorbing these hydrophobic li pase derivatives on several organic polymer beads. The immobilized enz ymes were more thermostable in organic solvents compared to the native and modified lipases. Thermostability was highest with XAD2 beads, fo llowed by XAD7 and RCOOH. Initially modifying the enzyme with hydropho bic modifiers did not have any effect on the enzyme thermostability. T he best conditions for storing these enzyme preparations were at very low temperature in the lyophilized form and in a solution containing t he reaction substrate. Interestingly, PEG-lipase immobilized on XAD7 b eads showed increased operational stability when used in a stirred-tan k reactor. The operational stability was further increased by a mild g lutaraldehyde treatment of the enzyme preparation.