L-gulonate + NAD(+) => 3-dehydro-L-gulonate + NADH + H(+)
l-gulonate + nad(+) => 3-dehydro-l-gulonate + nadh + h(+)
L-gulonate + NAD(+) => 3-dehydro-L-gulonate + NADH + H(+)
l-gulonate + nad(+) => 3-dehydro-l-gulonate + nadh + h(+)