label: (2E)-butenoyl-CoA + reduced [electron-transfer flavoprotein] => butanoyl-CoA + oxidized [electron-transfer flavoprotein] + H(+)
label_lc: (2e)-butenoyl-coa + reduced [electron-transfer flavoprotein] => butanoyl-coa + oxidized [electron-transfer flavoprotein] + h(+)