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| Cellulase | |||||||||
|---|---|---|---|---|---|---|---|---|---|
 A cellulase enzyme produced by Thermomonospora fusca, with cellotriose bound in the shallow groove of the catalytic domain | |||||||||
| Identifiers | |||||||||
| EC no. | 3.2.1.4 | ||||||||
| CAS no. | 9012-54-8 | ||||||||
| Databases | |||||||||
| IntEnz | IntEnz view | ||||||||
| BRENDA | BRENDA entry | ||||||||
| ExPASy | NiceZyme view | ||||||||
| KEGG | KEGG entry | ||||||||
| MetaCyc | metabolic pathway | ||||||||
| PRIAM | profile | ||||||||
| PDB structures | RCSB PDB PDBe PDBsum | ||||||||
| Gene Ontology | AmiGO / QuickGO | ||||||||
| |||||||||
Cellulase (EC 3.2.1.4; systematic name 4-β-D-glucan 4-glucanohydrolase) is any of several enzymes produced chiefly by fungi, bacteria, and protozoans that catalyze cellulolysis, the decomposition of cellulose and of some related polysaccharides:
- Endohydrolysis of (1→4)-β-D-glucosidic linkages in cellulose, lichenin and cereal β-D-glucan
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 β-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-β-D-glycosidic linkages in cellulose, hemicellulose, lichenin, and cereal β-D-glucans. Because cellulose molecules bind strongly to each other, cellulolysis is relatively difficult compared to the breakdown of other polysaccharides such as starch.[2]
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 animals, such as some termites, snails,[3][4][5] 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.[6]
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-β-D-glucanase (β-1,4-glucanase, β-1,4-endoglucan hydrolase, endoglucanase D, 1,4-(1,3;1,4)-β-D-glucan 4-glucanohydrolase), carboxymethyl cellulase (CMCase), avicelase, celludextrinase, cellulase A, cellulosin AP, alkali cellulase, cellulase A 3, 9.5 cellulase, celloxylanase and pancellase SS. Enzymes that cleave lignin have occasionally been called cellulases, but this old usage is deprecated; they are lignin-modifying enzymes.
- ^ PDB: 1NLR; Sulzenbacher G, Shareck F, Morosoli R, Dupont C, Davies GJ (December 1997). "The Streptomyces lividans family 12 endoglucanase: construction of the catalytic core, expression, and X-ray structure at 1.75 Å resolution". Biochemistry. 36 (51): 16032–9. doi:10.1021/bi972407v. PMID 9440876.; rendered with PyMOL
- ^ Barkalow DG, Whistler RL. "Cellulose". AccessScience, McGraw-Hill.[permanent dead link]
- ^ Bignell DE, Roisin Y, Lo N (2011). Biology of termites: a modern synthesis. Dordrecht: Springer. ISBN 978-9048139767.
- ^ Watanabe H, Noda H, Tokuda G, Lo N (July 1998). "A cellulase gene of termite origin". Nature. 394 (6691): 330–1. Bibcode:1998Natur.394..330W. doi:10.1038/28527. PMID 9690469. S2CID 4384555.
- ^ Watanabe H, Tokuda G (August 2001). "Animal cellulases". Cellular and Molecular Life Sciences. 58 (9): 1167–78. doi:10.1007/PL00000931. PMID 11577976. S2CID 570164.
- ^ Guerriero, Gea; Sergeant, Kjell; Legay, Sylvain; Hausman, Jean-Francois; Cauchie, Henry-Michel; Ahmad, Irshad; Siddiqui, Khawar (2018-06-15). "Novel Insights from Comparative In Silico Analysis of Green Microalgal Cellulases". International Journal of Molecular Sciences. 19 (6): 1782. doi:10.3390/ijms19061782. ISSN 1422-0067. PMC 6032398. PMID 29914107.