The enzyme catalyses a step of the pentose phosphate pathway. The enzyme from the Gram-positive bacterium Leuconostoc mesenteroides prefers NADP+ while the enzyme from the Gram-negative bacterium Gluconacetobacter xylinus prefers NAD+. cf. EC
1.1.1.49, glucose-6-phosphate dehydrogenase (NADP+) and EC
1.1.1.388, glucose-6-phosphate dehydrogenase (NAD+).