Lipoprotein lipase immobilization onto copolypeptide fibers.

Abstract

Water insoluble lipoprotein lipase was prepared by immobilizing lipoprotein lipase (LPL) onto the surface of copolypeptide fibers with and without oligoglycine spacer. As sample fiber, copoly (L-glutamic acid/L-leucine) (PLGA-co-PLL) and copoly (γ-methyl-L-glutamate/L-leucine) (PMLG-co-PLL) were prepared. The mode of the immobilization between LPL and copolypeptide fibers such as a covalent fixation or an ionic interaction on the enzymatic activity and stability of the immobilized LPL was investi-gated. The retained activity of the LPL covalently immobilized by the azide method was found to be ex-cellent toward the small ester substrate, p-Nitrophenyl laurate (pNPL), compared to that by the peptide binding method. The values of the Michaelis constant Km and the maximum reaction velocity Vm for free and the immobilized LPL on the polypeptide fibers are estimated. The apparent Km was larger for immo-bilized LPL than for the free one, while Vm was smaller for the immobilized LPL. The thermal stability of the covalently immobilized LPL was higher than that of free LPL. The initial enzymatic activity of the covalently immobilized LPL almost unchanged without any definite elimination and inactivation of LPL, when the batch enzyme reaction was performed repeatedly, indicating the excellent durability.