Protease Immobilization onto Poly (γ-methyl-D-glutamate) Fibers

Water-insoluble protease, such as papain or ficin, was fixed by covalent bond onto the surface of poly (γ-methyl-D-glutamate) [PMDG] fibers, and the relative activity and the stability of the immobilized protease were investigated. The retained activity of protease covalently immobilized onto PMDG fibers was found to be excellent toward a small ester substrate, N-benzyl-L-arginine ethyl ester [BAEE]. The values of the Michaelis constant (Km) and the maximum reaction velocity (Vm) for free and the immobilized protease onto the PMDG fibers were estimated. The apparent Km was larger for immobilized protease than for the free enzyme, while Vm was smaller for the immobilied protease. The thermal stability of the covalently immobilized protease was higher than that of the free one. The initial enzymatic activity of the covalently immobilized protease remained approximately unchanged with storage time, when the batch enzyme reaction was performed repeatedly, indicating the excellent durability.