NADP-dependent D-xylose dehydrogenase catalyzing the oxydation of D-xylose into D-xylonolactone (By similarity). May also display activity with other sugars. May play a role in the regeneration of NADP(+) in the presence of these sugars (Probable). D-xylose + NADP(+) = D-xylono-1,5-lactone + H(+) + NADPH Belongs to the Gfo/Idh/MocA family.