Xylose fermentation by yeasts

Summary Xylose reductase from the xylose-fermenting yeastPichia stipitis was purified to electrophoretic homogeneity via ion-exchange, gel and affinity chromatography. At physiological pH values the thermodynamic equilibrium constant was determined to be 0.575x10¹⁰ (l·mol^-1). Product inhibiton studies are reported which clearly show that the kinetic mechanism of the xylose reductase is ordered-bi-bi with isomerisation of a stable enzyme form.