LIPOPROTEIN-LIPASE IMMOBILIZATION ONTO POROUS POLYVINYL-ALCOHOL BEADS

Water-insoluble proteases were prepared by immobilizing lipoprotein lipase (LPL) onto the surface of porous polyvinyl alcohol (PVA) beads by covalent fixation. The relative activity of the immobilized proteases was found to remain high toward small ester substrates, p-nitrophenyl laurate (pNPL). The relative activity of the immobilized 1,PL by cyanogen bromide (CNBr) method decreased gradually with the decreasing surface concentration of the immobilized LPL on the porous PVA beads. On the contrary, the immobilized 1,PL by hexamethylene diisocyanate (HMDI) method gave an almost constant activity for the substrate hydrolysis within the surface concentration region studied and gave higher relative activity (RA) than that by the CNBr method. The Michaelis constant, K(m), and the maximum reaction velocity, V(m), were estimated for the free and the immobilized LPL. The apparent K(m) was larger for the immobilized LPL than for the free one, and V(m) was smaller for the immobilized LPL. The pH, thermal, and storage stabilities of the immobilized LPL were higher than those of the free ones. The initial enzymic activity of the immobilized LPL maintained almost unchanged without any leakage and inactivation of LPL when the batch enzymic reaction was performed repeatedly, indicating excellent durability of the immobilized LPL. (C) 1993 John Wiley & Sons, Inc.