2-dehydro-D-gluconate + A => 2,5-didehydro-D-gluconate + AH2
2-dehydro-d-gluconate + a => 2,5-didehydro-d-gluconate + ah2
2-dehydro-D-gluconate + A => 2,5-didehydro-D-gluconate + AH2
2-dehydro-d-gluconate + a => 2,5-didehydro-d-gluconate + ah2