Characterization of a recombinant mannobiose 2-epimerase from Spirochaeta thermophila that is suggested to be a cellobiose 2-epimerase
A purified recombinant enzyme from Spirochaeta thermophila, that is suggested to be a cellobiose 2-epimerase, was a 47 kDa monomer with a specific activity of 29.2 U min⁻¹ for mannobiose. The epimerization activity of the recombinant enzyme for mannobiose was maximal at pH 7.0 and 60 °C with a half-...
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Veröffentlicht in: | Biotechnology letters 2013-11, Vol.35 (11), p.1873-1880 |
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Zusammenfassung: | A purified recombinant enzyme from Spirochaeta thermophila, that is suggested to be a cellobiose 2-epimerase, was a 47 kDa monomer with a specific activity of 29.2 U min⁻¹ for mannobiose. The epimerization activity of the recombinant enzyme for mannobiose was maximal at pH 7.0 and 60 °C with a half-life of 124 h. The enzyme exhibited a higher epimerization activity for mannose or the mannose moiety at the reducing end of β- and α-1,4-glycosyl-mannose than for glucose or the glucose moiety of β- and α-1,4-glycosyl-glucose. The enzyme was identified as a mannobiose 2-epimerase by evaluating its substrate specificity with not only glucose-containing sugars but also mannose-containing sugars. The activities of the reported cellobiose 2-epimerases from Caldicellulosiruptor saccharolyticus, Dictyoglomus turgidum and Ruminococcus marinus for mannobiose were higher than those for cellobiose, strongly suggesting that these enzymes are not cellobiose 2-epimerases but are mannobiose 2-epimerases. |
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ISSN: | 0141-5492 1573-6776 |
DOI: | 10.1007/s10529-013-1267-6 |