D-glucose + NAD(+) = D-glucono-1,5-lactone + H(+) + NADH D-glucose + NADP(+) = D-glucono-1,5-lactone + H(+) + NADPH Homotetramer. Prefers NAD to NADP; very unstable compared to the other isoenzymes and 2M NaCl enhances its pH and thermostability. Belongs to the short-chain dehydrogenases/reductases (SDR) family.