butanoyl-CoA + 2 reduced [2Fe-2S]-[ferredoxin] + 2 NAD(+) <=> (2E)-butenoyl-CoA + 2 oxidized [2Fe-2S]-[ferredoxin] + 2 NADH
butanoyl-coa + 2 reduced [2fe-2s]-[ferredoxin] + 2 nad(+) <=> (2e)-butenoyl-coa + 2 oxidized [2fe-2s]-[ferredoxin] + 2 nadh