Evidence that the gene YLR070c of Saccharomyces cerevisiae encodes a xylitol dehydrogenase

The open reading frame YLR070c of Saccharomyces cerevisiae has high sequence similarity to S. cerevisiae sorbitol dehydrogenase and to xylitol dehydrogenase of Pichia stipitis. Overexpression of this open reading frame in S. cerevisiae resulted in xylitol dehydrogenase activity. The enzyme is specific for NADH. The following Michaelis constants were estimated: D-xylulose, 1.1 mM; NADH, 240 microM (at pH 7.0); xylitol, 25 mM; NAD, 100 microM (at pH 9.0). Xylitol dehydrogenase activity with the same kinetic properties can also be induced by xylose in wild type S. cerevisiae cells.