C-2 Epimer Formation of Tetrose, Pentose and Hexose Sugars by Xylose Isomerase

Author: Vuolanto Antti   Pastinen Ossi   Schoemaker Hans E.   Leisola Matti  

Publisher: Informa Healthcare

ISSN: 1024-2422

Source: Biocatalysis and Biotransformation, Vol.20, Iss.4, 2002-01, pp. : 235-240

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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.