Substrate specificity of a recombinant ribose-5-phosphate isomerase from <Emphasis Type="Italic">Streptococcus pneumoniae</Emphasis> and its application in the production of <Emphasis Type="SmallCaps">l</Emphasis>-lyxose and <Emphasis Type="SmallCaps">l</Emphasis>-tagatose |
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Authors: | Chang-Su Park Soo-Jin Yeom Yu-Ri Lim Yeong-Su Kim Deok-Kun Oh |
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Institution: | (1) Department of Bioscience and Biotechnology, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, 143-701, South Korea; |
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Abstract: | A putative ribose-5-phosphate isomerase (RpiB) from Streptococcus pneumoniae was purified with a specific activity of 26.7 U mg−1 by Hi-Trap Q HP anion exchange and Sephacryl S-300 HR 16/60 gel filtration chromatographies. The native enzyme existed as
a 96-kDa tetramer with activity maxima at pH 7.5 and 35°C. The RpiB exhibited isomerization activity with l-lyxose, l-talose, d-gulose, d-ribose, l-mannose, d-allose, l-xylulose, l-tagatose, d-sorbose, d-ribulose, l-fructose, and d-psicose and exhibited particularly high activity with l-form monosaccharides such as l-lyxose, l-xylulose, l-talose, and l-tagatose. With l-xylulose (500 g l−1) and l-talose (500 g l−1) substrates, the optimum concentrations of RpiB were 300 and 600 U ml−1, respectively. The enzyme converted 500 g l−1
l-xylulose to 350 g l−1
l-lyxose after 3 h, and yielded 450 g l−1
l-tagatose from 500 g l−1
l-talose after 5 h. These results suggest that RpiB from S. pneumoniae can be employed as a potential producer of l-form monosaccharides. |
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