(3S,4R)-3,4-dihydroxycyclohexa-1,5-diene-1,4-dicarboxylate + NAD(+) <=> 3,4-dihydroxybenzoate + CO2 + NADH
(3s,4r)-3,4-dihydroxycyclohexa-1,5-diene-1,4-dicarboxylate + nad(+) <=> 3,4-dihydroxybenzoate + co2 + nadh