Mediates the conversion of 2'-dehydrokanamycin A into kanamycin A. 2'-dehydrokanamycin A + H(+) + NADPH = kanamycin A + NADP(+) Antibiotic biosynthesis; kanamycin biosynthesis. Belongs to the NAD(P)-dependent epimerase/dehydratase family. Truncated N-terminus. Truncated N-terminus.