Active towards the soluble carboxymethylcellulose (CMC). Possesses expansin activity too. Endohydrolysis of (1->4)-beta-D-glucosidic linkages in cellulose, lichenin and cereal beta-D-glucans. Optimum pH is 4.6. Optimum temperature is 30-50 degrees Celsius. Digestive gland. Belongs to the glycosyl hydrolase 45 (cellulase K) family.