title: Substrate specificity of family 5, 6, 7, 9, 12, and 45 endoglucanases.
abstract: Endoglucanases are important enzymes for biomass conversion and other industrial processes. Determining the specificity of endoglucanases from various glycoside hydrolase families is of interest for bioinformatic functional prediction and substrate-tailored enzyme development. To do so, we characterized approximately 30 endoglucanases from six glycoside hydrolase families. For p-nitrophenyl cellobioside and lactoside, only family 7 enzymes showed significant activity. For xyloglucan, both family 7 and 12 enzymes showed significant activity. For xylan and arabinoxylan, only family 7 enzymes showed significant activity. For mannan and galactomannan, both family 5 and 9 enzymes showed significant activity. The difference in specificity was preliminarily attributed mainly to the structural difference of the enzymes' active sites. For family 7 endoglucanases, difference in thermal stability might affect their performance in hydrolyzing various (hemi)cellulose substrates. Phylogenetic analysis on the subfamily distribution of family 5 endoglucanases (in relation with mannanases) suggested that their mannanase side-activity might be the remnant of an ancestral multi-function enzyme. Similar analysis was also made with the xyloglucanase or arabionxylans side-activity of family 12 and 7 endoglucanases. The apparent dependence of the specificity on family (primary/tertiary structure) might assist us in better understanding the structure-function relationship of the enzymes, and developing more versatile biocatalysts for the utilization of biomass.
authors.affiliation: Novozymes Inc., Davis, CA 95618, USA.
authors.forename: E
authors.initials: E
authors.lastname: Vlasenko
authors.forename: M
authors.initials: M
authors.lastname: Schülein
authors.forename: J
authors.initials: J
authors.lastname: Cherry
authors.forename: F
authors.initials: F
authors.lastname: Xu
mesh_terms: D055162:Biocatalysis; D002480:Cellulase / Q000235:genetics / Q000378:metabolism*; D002482:Cellulose / Q000378:metabolism; D004795:Enzyme Stability; D005690:Galactose / Q000031:analogs & derivatives; D008351:Mannans / Q000378:metabolism; D005810:Multigene Family / Q000235:genetics*; D010802:Phylogeny; D011134:Polysaccharides / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature; D014990:Xylans / Q000378:metabolism
chemical_list: D008351:Mannans; D011134:Polysaccharides; D014990:Xylans; C012990:galactomannan; C007916:hemicellulose; D002482:Cellulose; C085118:arabinoxylan; D002480:Cellulase; D005690:Galactose