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PROSITE documentation PDOC00877 [for PROSITE entry PS01140]

Glycosyl hydrolases family 45 active site


The microbial degradation of cellulose and xylans requires several types of enzymes such as endoglucanases (EC, cellobiohydrolases (EC (exoglucanases), or xylanases (EC [1,2]. Fungi and bacteria produces a spectrum of cellulolytic enzymes (cellulases) and xylanases which, on the basis of sequence similarities, can be classified into families. One of these families is known as the cellulase family K or as the glycosyl hydrolases family 45 [3,E1]. The enzymes which are currently known to belong to this family are listed below.

  • Endoglucanase 5 from Humicola insolens.
  • Endoglucanase 5 from Trichoderma reesei (egl5).
  • Endoglucanase K from Fusarium oxysporum.
  • Endoglucanase B from Pseudomonas fluorescens (celB).
  • Endoglucanase 1 from Ustilago maydis (egl1).

The best conserved regions in these enzymes is located in the N-terminal section. It contains an aspartic acid residue which has been shown [4] to act as a nucleophile in the catalytic mechanism. We use this region as a signature pattern.

Expert(s) to contact by email:

Henrissat B.

Last update:

November 1997 / Pattern and text revised.


Technical section

PROSITE method (with tools and information) covered by this documentation:

GLYCOSYL_HYDROL_F45, PS01140; Glycosyl hydrolases family 45 active site  (PATTERN)


1AuthorsBeguin P.
TitleMolecular biology of cellulose degradation.
SourceAnnu. Rev. Microbiol. 44:219-248(1990).
PubMed ID2252383

2AuthorsGilkes N.R. Henrissat B. Kilburn D.G. Miller R.C. Jr. Warren R.A.J.
TitleDomains in microbial beta-1, 4-glycanases: sequence conservation, function, and enzyme families.
SourceMicrobiol. Rev. 55:303-315(1991).
PubMed ID1886523

3AuthorsHenrissat B. Bairoch A.
TitleNew families in the classification of glycosyl hydrolases based on amino acid sequence similarities.
SourceBiochem. J. 293:781-788(1993).
PubMed ID8352747

4AuthorsDavies G.J. Dodson G.G. Hubbard R.E. Tolley S.P. Dauter Z. Wilson K.S. Hjort C. Mikkelsen J.M. Rasmussen G. Schuelein M.
TitleStructure and function of endoglucanase V.
SourceNature 365:362-364(1993).
PubMed ID8377830


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