Fusion Endoglucanase Cel12B from Thermotoga maritima with Cellulose Binding Domain

Abstract

Four fusion enzymes were expressed in Escherichia coli BL21 (DE3), and their properties against sodium carboxymethyl cellulose (CMC-Na) and microcrystalline cellulose were characterized. When endoglucanase cel12B genes fused with the cellulose binding domain (CBD) of the N-terminal of xylanases from Thermotoga maritima and Thermotoga thermarum, CBD1, CBD2, CBD3, and CBD4 fusion proteins were obtained. The four fusion proteins exhibited a certain adsorption of microcrystalline cellulose, and CBD4 showed the best performance. In addition, the optimum pH and temperature of fusion proteins were all somewhat decreased, and they became more sensitive to cations. The CBD1, CBD2, CBD3, and CBD4 displayed some enzyme activity towards microcrystalline cellulose; however, the CMC-Na enzyme activity was remarkably reduced.