Preparation of D-xylulose from D-xylose

Abstract

A simple method is described for the preparation of d-xylulose. It consists of the isomerization of d-xylose with xylose isomerase (EC 5.3.1.5), yielding an equilibrium mixture of d-xylulose and d-xylose. This is followed by the quantitative oxidation of residual d-xylose to d-xylonic acid with immobilized A. calcoaceticus cells. A combination of methanol precipitation and ion exchange is used for the removal of xylonic acid. This procedure offers many advantages over existing methods for the preparation of d-xylulose. The purity of the final product compares favorably to that of a commercial d-xylulose preparation.