Cellulase

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 in their bodies, and are therefore unable to use most of the energy contained in plant material.

Enzymes which hydrolyze Hemicellulose are usually referred to as hemicellulase and are usually classified under cellulase in general. Enzymes that cleave lignin are occasionally classified as cellulase, but this is usually considered erroneous.

Three general types of enzymes make up the cellulase enzyme complex. Endocellulase breaks internal bonds to disrupt the crystalline structure of cellulose and expose individual cellulase polysaccharide chains. Exocellulase cleaves 2-4 units from the ends of the exposed chains produced by endocellulase, resulting in the tetrasaccharides or disaccharide such as cellobiose. Cellobiase or beta-glucosidase hydrolyses the endocellulase product into individual monosaccharides.

Within the above types there are also progressive and non-progressive types. Progressive cellulase will continue to interact with a single polysacchaide strand, non-progressive cellulase will interact once then disengage and engage another polysacchaide strand.

Cellulase is used for commercial food processing in coffee. It performs hydrolysis of cellulose during drying of beans. Cellulase is used in the fermentation of biomass into biofuels, although this process is relatively experimental at present. Cellulase is used as a treatment for Phytobezoars, a form of cellulose bezoar found in the human stomach.

Other enzyme companies such as Dyadic International, Inc. (AMEX: DIL) have been using fungi to develop and manufacture cellulases in 150,000 liter industrial fermenters since 1994. With the advent of genetic engineering and genomics companies like Dyadic, Genencor and Novozymes have the modern biological tools such as Dyadic's patented C1 Host Technology [1] to develop and manufacture large volumes of new and better performing enzyme mixtures to make the production of cellulosic ethanol more economical.

Cellulase Types & Action

Cellulase Mechanism

Generalized reaction of beta glucosidase enzymes such as cellulase

References

• Chapin III, F.S., P.A. Matson, H.A. Mooney. Principles of Terrestrial Ecosystem Ecology. Springer-Verlag New York, NY. 2002
• The Merck Manual of Diagnosis and Therapy, Chapter 24