Cellulase
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Cellulase is an enzyme complex which breaks down cellulose to beta-glucose. It is produced mainly by symbiotic bacteria in the ruminating chambers of herbivores. Aside from ruminants, most animals (including humans) do not produce cellulase, and are therefore unable to use most of the energy contained in plant material.
Three types of enzymes make up the cellulase enzyme complex. Endocellulase breaks internal bonds to disrupt the crystalline structure of cellulose. Exocellulase cleaves two-glucose units from the ends of the smaller chains produced by endocellulase, resulting in the disaccharide cellobiose. Cellobiase or beta-glucosidase cleaves the beta linkage between the two glucose molecules in cellobiose. (Source: Chapin III, F.S., P.A. Matson, H.A. Mooney. 2002. Principles of Terrestrial Ecosystem Ecology. Springer-Verlag New York, NY.)
Cellulase is also used for commercial food processing in coffee. It performs hydrolysis of cellulose during drying of beans.