Acyl-CoA dehydrogenase that exhibits broad specificity for linear acyl-CoA substrates, with a preference for long-chain substrates. a long-chain 2,3-saturated fatty acyl-CoA + H(+) + oxidized [electron-transfer flavoprotein] = a long-chain (2E)-enoyl-CoA + reduced [electron-transfer flavoprotein] a medium-chain 2,3-saturated fatty acyl-CoA + H(+) + oxidized [electron-transfer flavoprotein] = a medium-chain (2E)-enoyl-CoA + reduced [electron-transfer flavoprotein] a short-chain 2,3-saturated fatty acyl-CoA + H(+) + oxidized [electron-transfer flavoprotein] = a short-chain (2E)-enoyl-CoA + reduced [electron-transfer flavoprotein] H(+) + octadecanoyl-CoA + oxidized [electron-transfer flavoprotein] = (2E)-octadecenoyl-CoA + reduced [electron-transfer flavoprotein] H(+) + hexadecanoyl-CoA + oxidized [electron-transfer flavoprotein] = (2E)-hexadecenoyl-CoA + reduced [electron-transfer flavoprotein] dodecanoyl-CoA + H(+) + oxidized [electron-transfer flavoprotein] = (2E)-dodecenoyl-CoA + reduced [electron-transfer flavoprotein] decanoyl-CoA + H(+) + oxidized [electron-transfer flavoprotein] = (2E)-decenoyl-CoA + reduced [electron-transfer flavoprotein] H(+) + hexanoyl-CoA + oxidized [electron-transfer flavoprotein] = (2E)-hexenoyl-CoA + reduced [electron-transfer flavoprotein] butanoyl-CoA + H(+) + oxidized [electron-transfer flavoprotein] = (2E)-butenoyl-CoA + reduced [electron-transfer flavoprotein] kcat is 1.07 sec(-1) with butanoyl-CoA as substrate. kcat is 0.80 sec(-1) with hexanoyl-CoA as substrate. kcat is 0.61 sec(-1) with octadecanoyl-CoA as substrate. Lipid metabolism; fatty acid metabolism. Homodimer. Belongs to the acyl-CoA dehydrogenase family.