کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
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70089 | 48809 | 2011 | 7 صفحه PDF | دانلود رایگان |
Cellulose saccharification is an important process in conversion from lignocellulosic biomass to biofuels and other chemicals, and requires concerted action of endocellulase, exocellulase and β-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-β-1,4-glucanase activity of 220 U mg−1 against carboxymethylcellulose and exo-β-1,4-glucanase activity of 52.9 U mg−1 against 4-nitrophenyl-β-d-cellobioside, 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.
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► Rucel5B is a cellulase possessing both endo- and exo-β-1,4-glucanase activities.
► Its activities against CMC and pNPC were 220 and 52.9 U mg−1, respectively.
► Rucel5B could hydrolyze both amorphous and crystalline cellulose.
Journal: Journal of Molecular Catalysis B: Enzymatic - Volume 73, Issues 1–4, December 2011, Pages 104–110