page_title: Cellulase
hierarchical_section_title: Cellulase
caption_attribution_description: Secondary/tertiary structure ribbon diagram of the Streptomyces lividans beta-1,4-endoglucanase catalytic domain (PDB 1NLR) rendered using PyMol (DeLano Scientific)
context_page_description: Cellulase is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysaccharides. The name is also used for any naturally occurring mixture or complex of various such enzymes, that act serially or synergistically to decompose cellulosic material.
  Cellulases break down the cellulose molecule into monosaccharides such as beta-glucose, or shorter polysaccharides and oligosaccharides. Cellulose breakdown is of considerable economic importance, because it makes a major constituent of plants available for consumption and use in chemical reactions. The specific reaction involved is the hydrolysis of the 1,4-beta-D-glycosidic linkages in cellulose, hemicellulose, lichenin, and cereal beta-D-glucans. Because cellulose molecules bind strongly to each other, cellulolysis is relatively difficult compared to the breakdown of other polysaccharides such as starch.
  Most mammals have only very limited ability to digest dietary fibres like cellulose by themselves.
context_section_description: Cellulase is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysaccharides. The name is also used for any naturally occurring mixture or complex of various such enzymes, that act serially or synergistically to decompose cellulosic material.
  Cellulases break down the cellulose molecule into monosaccharides ("simple sugars") such as beta-glucose, or shorter polysaccharides and oligosaccharides.  Cellulose breakdown is of considerable economic importance, because it makes a major constituent of plants available for consumption and use in chemical reactions. The specific reaction involved is the hydrolysis of the 1,4-beta-D-glycosidic linkages in cellulose, hemicellulose, lichenin, and cereal beta-D-glucans. Because cellulose molecules bind strongly to each other, cellulolysis is relatively difficult compared to the breakdown of other polysaccharides such as starch.
  Most mammals have only very limited ability to digest dietary fibres like cellulose by themselves. In many herbivorous animals such as ruminants like cattle and sheep and hindgut fermenters like horses, cellulases are produced by symbiotic bacteria. Endogenous cellulases are produced by a few types of metazoan animals, such as some termites, snails, and earthworms.
  Recently, cellulases have also been found in green microalgae (Chlamydomonas reinhardtii, Gonium pectorale and Volvox carteri) and their catalytic domains (CD) belonging to GH9 Family show highest sequence homology to metazoan endogenous cellulases. Algal cellulases are modular, consisting of putative novel cysteine-rich
  carbohydrate-binding modules (CBMs), proline/serine-(PS) rich linkers in addition to putative Ig-like and unknown domains in some members. Cellulase from Gonium pectorale consisted of two CDs separated by linkers and with a C-terminal CBM.
  Several different kinds of cellulases are known, which differ structurally and mechanistically.  Synonyms, derivatives, and specific enzymes associated with the name "cellulase" include endo-1,4-beta-D-glucanase (beta-1,4-glucanase, beta-1,4-endoglucan hydrolase, endoglucanase D, 1,4-(1,3,1,4)-beta-D-glucan 4-glucanohydrolase), carboxymethyl cellulase (CMCase), avicelase, celludextrinase, cellulase A, cellulosin AP, alkali cellulase, cellulase A 3, 9.5 cellulase, and pancellase SS. Enzymes that cleave lignin have occasionally been called cellulases, but this old usage is deprecated; they are lignin-modifying enzymes.
caption: Ribbon representation of the Streptomyces lividans beta-1,4-endoglucanase catalytic domain - an example from the family 12 glycoside hydrolases[1]
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