Cellulose binding domain from Clostridium cellulovorans as a paper modification reagent

Cellulose-binding domains have been isolated from various cellulases, and proteins, which lack hydrolytic activity. Two cellulose-binding domains from Clostridium cellulovorans were fused to form a cellulose crosslinking protein (CCP). The recombinant bifunctional protein was tested as a wet-end dry-strength agent and as a surface or internal sizing agent. The purified protein improved mechanical properties (tensile strength, stretch at break and tensile energy absorption). Furthermore, a synergistic effect between CCP and cationic starch (CS) was observed that resulted in higher mechanical performance. CCP sizing potential was also shown, internally and on the surface of papers employing different methods of application. The binding of cellulose-binding domains to cellulose, under a wide range of environmental conditions, without need for chemical reactions, makes them attractive moieties for the design of a new class of paper-modification materials that are environmentally friendly.