Analysis of Structure and Key Amino Acids Existed in 4α Glucanotransferase Catalytic Region

Abstract:

4α glucanotransferase(4αGtase) has the ability of catalyzing starch to form large ring cyclodextrin(LR-CD). In this study,in order to analyze the structure characteristics and key amino acid in the catalytic region,series of amino acids modifiers,such as arginine modifier DIC,methionine modifier Ch-T,tryptophan modifier NBS,histidine modifier DEPC,carboxyl modifier EDC,disulfide bond modifier DTT and protein denaturant mercaptoethanol,were applied to modify the 4αGtase,respectively. Results showed that the key amino acids existed in active center of4αGtase are histidine,glutamic acid/aspartic acid. The disulfide bond is very important to stabilize the activity of 4αGtase. From these results we deduced that 4αGtase contained two domains inactivity center,methionine and tryptophan are in different region of these two domain. A proper change of spatial structure will promote the combination of enzyme with starch to increase the total activity of 4αGtase.