title: Characterization of a recombinant cellobiose 2-epimerase from Caldicellulosiruptor saccharolyticus and its application in the production of mannose from glucose.
abstract: A putative N-acyl-D-glucosamine 2-epimerase from Caldicellulosiruptor saccharolyticus was cloned and expressed in Escherichia coli. The recombinant enzyme was identified as a cellobiose 2-epimerase by the analysis of the activity for substrates, acid-hydrolyzed products, and amino acid sequence. The cellobiose 2-epimerase was purified with a specific activity of 35 nmol min(-1) mg(-1) for D-glucose with a 47-kDa monomer. The epimerization activity for D-glucose was maximal at pH 7.5 and 75°C. The half-lives of the enzyme at 60°C, 65°C, 70°C, 75°C, and 80°C were 142, 71, 35, 18, and 4.6 h, respectively. The enzyme catalyzed the epimerization reactions of the aldoses harboring hydroxyl groups oriented in the right-hand configuration at the C2 position and the left-hand configuration at the C3 position, such as D-glucose, D-xylose, L-altrose, L-idose, and L-arabinose, to their C2 epimers, such as D-mannose, D-lyxose, L-allose, L-gulose, and L-ribose, respectively. The enzyme catalyzed also the isomerization reactions. The enzyme exhibited the highest activity for mannose among monosaccharides. Thus, mannose at 75 g l(-1) and fructose at 47.5 g l(-1) were produced from 500 g l(-1) glucose at pH 7.5 and 75°C over 3 h by the enzyme.
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, Seoul, Republic of Korea.
authors.forename: Chang-Su
authors.initials: CS
authors.lastname: Park
authors.forename: Jung-Eun
authors.initials: JE
authors.lastname: Kim
authors.forename: Jin-Geun
authors.initials: JG
authors.lastname: Choi
authors.forename: Deok-Kun
authors.initials: DK
authors.lastname: Oh
mesh_terms: D001419:Bacteria / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D055162:Biocatalysis; D002475:Cellobiose / Q000378:metabolism*; D003001:Cloning, Molecular; D004795:Enzyme Stability; D005947:Glucose / Q000378:metabolism*; D007700:Kinetics; D008358:Mannose / Q000378:metabolism*; D019998:Racemases and Epimerases / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; D002475:Cellobiose; D019998:Racemases and Epimerases; D005947:Glucose; D008358:Mannose