Abstract
In the detergent industry, fungal endoglucanases are used to release microfibrils from the surfaces of dyed cellulosic fabrics to enhance color brightness. Family 45 endoglucanase (family 45 glycoside hydrolase, GH45) EGL3 from Humicola grisea is more resistant to anionic surfactants and oxidizing agents than family 45 endoglucanase RCE1 from Rhizopus oryzae, while in the present study, a catalytic domain of RCE1 had higher defibrillation activity on dyed cotton fabrics than did that of EGL3. To identify the amino acid regions involved in these properties, we compared the characteristics of RCE1, EGL3, and three chimeric enzymes, in which each of the three regions of the catalytic domain of EGL3 was replaced by the corresponding region of the catalytic domain of RCE1. Amino acids in the N-terminal region were involved in resistance to anionic surfactants and oxidizing agents. Furthermore, amino acids in the region adjacent to the N-terminal region were involved in releasing microfibrils and in binding to dyed cotton fabrics, indicating that the binding of the amino acids in this region might be important in the release of microfibrils from dyed cotton fabrics.
