Catalyzes the NADP(+)-dependent oxidation of D-xylose. Is able to use both NADP(+) and NAD(+); however, the enzyme shows a very strong preference for NADP(+). Is likely involved in the first step of the oxidative D-xylose degradation pathway. D-xylose + NADP(+) = D-xylono-1,5-lactone + H(+) + NADPH D-xylose + NAD(+) = D-xylono-1,5-lactone + H(+) + NADH Binds 2 Zn(2+) ions per subunit. kcat is 14.9 sec(-1). Carbohydrate metabolism; D-xylose degradation. Homotetramer. Is induced by D-xylose. No significant levels of expression can detected when the cells are grown on various other sugars such as L-xylose, L-arabinose, D-galactose, D-tagatose and D-glucose. Belongs to the Gfo/Idh/MocA family.