NADP-dependent D-xylose dehydrogenase involved in the degradation of D-xylose, a major component of hemicelluloses such as xylan. In addition to D-xylose, oxidizes D-ribose at similar kinetic constants, whereas D-glucose is oxidized with about 70-fold lower catalytic efficiency. D-xylofuranose + NADP(+) = D-xylono-1,4-lactone + H(+) + NADPH Optimum pH is 8.3. Homotretramer. Expression is induced during growth on D-xylose. Belongs to the Gfo/Idh/MocA family.