Studies on characteristics of immobilized papain on silk fibroin

Using the activated fibroin as carrier,the papain was immobilized using covalence-crosslinking method.Studies on some characteristics of the fibroin-immobilized papain showed: the K~(app)_m [casein] of the immobilized papain was 0.092%,and the K_m [casein] of the free papain was 0.198%,which mean the affinity of the immobilized papain for casein increased greatly,being 0.46 times of the free papain.The optimum pH value was 7.5 for the immobilized papain.The immobilized papain was stable under 6.5-8.0.The heat stability of the immobilized papain was 4-55 ℃.The operation half-life of the free papain was 38 d while the immobilized papain was 54 d.The operation half-life of the immobilized papain was longer than that of the free papain.