C-2 Epimer Formation of Tetrose, Pentose and Hexose Sugars by Xylose Isomerase |
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Authors: | Antti Vuolanto Ossi Pastinen Hans E. Schoemaker Matti Leisola |
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Affiliation: | a Laboratory of Bioprocess Engineering, Helsinki University of Technology, PO Box 6100, FIN- 02015 HUT, Finland.b DSM Research, Life Science Products, PO Box 18, 6160 MD Geleen, The Netherlands. |
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Abstract: | We describe novel tetrose isomerizations and C-2 epimerizations by the industrially important d -xylose ketol-isomerase (E.C.5.3.1.5) with both the d - and l -forms of the sugars. We further show that in addition to isomerization to d -fructose, d -glucose is slowly C-2 epimerized to d -mannose. The formation rate of the C-2 epimer was 0.03 mg mg -1 min -1 from d -glucose, 0.56 mg mg -1 min -1 from d -arabinose and 3.0 mg mg -1 min -1 from d -erythrose. The equilibria of the reaction products as a function of temperature were measured for threose/erythrulose/erythrose, arabinose/ribulose/ ribose and glucose/fructose/mannose. |
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Keywords: | Xylose Isomerase Glucose Isomerase C-2 Epimerization Tetroses Pentoses |
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