Characterization of a recombinant cellobiose 2-epimerase from Dictyoglomus turgidum that epimerizes and isomerizes β-1,4- and α-1,4-gluco-oligosaccharides.
A recombinant putative N-acyl-D-glucosamine 2-epimerase from Dictyoglomus turgidum was identified as a cellobiose 2-epimerase by evaluating its substrate specificity. The purified enzyme was a 46 kDa monomer with a specific activity of 16.8 μmol min(-1) mg(-1) for cellobiose. The epimerization activity was maximal at pH 7.0 and 70 °C with a half-life of 55 h. The isomerization of the glucose at the reducing end of β-1,4- and α-1,4-linked gluco-oligosaccharides to a fructose moiety by the enzyme took place after the epimerization of the glucose to a mannose moiety. The enzyme converted cellobiose to 12.8 % 4-O-β-D-glucopyranosyl-D-mannose and 54.6 % 4-O-β-D-glucopyranosyl-D-fructose as an equilibrium and converted lactose to 12.8 % epilactose and 54.3 % lactulose.
Department of Bioscience and Biotechnology, Konkuk University, Seoul, Republic of Korea.
Jung-Eun
JE
Kim
Yeong-Su
YS
Kim
Lin-Woo
LW
Kang
Deok-Kun
DK
Oh
D001419:Bacteria / Q000201:enzymology; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002238:Carbohydrate Epimerases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D002475:Cellobiose / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D003001:Cloning, Molecular; D004591:Electrophoresis, Polyacrylamide Gel; D004795:Enzyme Stability; D006863:Hydrogen-Ion Concentration; D007536:Isomerism; D009844:Oligosaccharides / Q000378:metabolism*; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D013379:Substrate Specificity; D013696:Temperature
D001426:Bacterial Proteins; D002352:Carrier Proteins; D009844:Oligosaccharides; D011994:Recombinant Proteins; D002475:Cellobiose; D002238:Carbohydrate Epimerases; C024519:N-acyl-D-glucosamine 2-epimerase