期刊
JOURNAL OF MOLECULAR CATALYSIS B-ENZYMATIC
卷 73, 期 1-4, 页码 104-110出版社
ELSEVIER
DOI: 10.1016/j.molcatb.2011.08.006
关键词
Cellulose saccharification; Function-based screening; Endocellulase; Exocellulase; Uncultured yak rumen microorganism
资金
- High-tech Research and Development Program of China [2007AA021302, 2008AA02Z311]
Cellulose saccharification is an important process in conversion from lignocellulosic biomass to biofuels and other chemicals, and requires concerted action of endocellulase, exocellulase and beta-glucosidase. Thus, it is very interesting to discover and develop multifunctional cellulase in order to convert cellulose to glucose more efficiently. Here we report an endo/exocellulase Rucel5B with 336 amino acids cloned from yak rumen uncultured microorganism, and its recombinant expression in Escherichia coli. This cellulase possesses endo-beta-1,4-glucanase activity of 220U mg(-1) against carboxymethylcellulose and exo-beta-1,4-glucanase activity of 52.9 U mg(-1) against 4-nitrophenyl-beta-Dcellobioside, and is able to hydrolyze not only amorphous cellulose (carboxymethylcellulose, barley glucan, lichenan, phosphate acid swollen cellulose. etc.), but also crystalline cellulose (filter paper, avicel, etc.). The exo-type action mode of Rucel5B was confirmed by its release of cellobiose from cellooligosaccharides and crystalline cellulose, and its endo-type action mode was confirmed by a time-dependent decrease in the polymerization degree of hydrolysates when Rucel5B was incubated with soluble amorphous cellulose. Therefore, the enzymatic activities, the endo/exo-mode of action and the ability in saccharification of both amorphous and crystalline cellulose make Recul5B a very interesting candidate for efficient saccharification of cellulose. (C) 2011 Elsevier B.V. All rights reserved.
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