Improving Paper Mechanical and Surface Properties by the Double Family1cellulose-binding Domains

摘要

Most cellulose-degrading enzymes have a two-domain structure that consists of a catalytic and a cellulose binding domain (CBD) connected by a linker region. CBDs promote the association of the enzyme with the substrate and play the important role in the enzymatic hydrolysis of cellulose material. CBDs have also been found in several polysaccharide-degrading enzymes other than cellulases, such as hemicellulase, endo-mannanase and acetyl xylan esterase. Based on sequence comparisons the CBDs have been grouped into several families. Family 1 CBDs from fungi are distinct from the other families in the size and structure. Many researchers have demonstrated that CBDs exists an immense potential for the application of the cellulose-binding domain in the field of fiber modification and paper industry. It is still no report about the roles of family 1 CBDs in improving mechanical and surface properties of paper. In this study, two peptides with double family 1 CBD from acetyl xylan esterase and endoglucanase from Volvariella volvacea was constructed respectively and expressed in E. coli. We further compared their binding capacities on cellulosic substrates and their improvement on paper properties. The purified dCBD (AXE1) and dCBD (EG1) protein increased the treated paper’s tensile strength, bursting strength and folding endurance by 10%, 8.7%, 30% and5.2%, 7.6%, 27.8% respectively. In addition, dCBD protein treatment was shown to transform filter paper into a more water-repellent paper. They can be used to design a new class of paper-modification materials