Analysis and prediction of the physiological effects of altered coenzyme specificity in xylose reductase and xylitol dehydrogenase during xylose fermentation by Saccharomyces cerevisiae

► Fermentation of xylose into ethanol is important in “biomass-to-biofuel” processes. ► Protein engineering has been extensively used to improve xylose fermentation. ► Published data on variants of XR and XDH are explored as predictors of strain performance. ► Applying internal reactant concentrations to bi-substrate kinetic equations give a reliable forecast on xylitol formation. ► A criterion of physiological fitness of engineered forms of XR is developed.