Short-chain specific acyl-CoA dehydrogenase is one of the acyl-CoA dehydrogenases that catalyze the first step of mitochondrial fatty acid beta-oxidation, an aerobic process breaking down fatty acids into acetyl-CoA and allowing the production of energy from fats. The first step of fatty acid beta-oxidation consists in the removal of one hydrogen from C-2 and C-3 of the straight-chain fatty acyl-CoA thioester, resulting in the formation of trans-2-enoyl-CoA (By similarity). Among the different mitochondrial acyl-CoA dehydrogenases, short-chain specific acyl-CoA dehydrogenase acts specifically on acyl-CoAs with saturated 4 to 6 carbons long primary chains (PubMed:6712627). a short-chain 2,3-saturated fatty acyl-CoA + H(+) + oxidized [electron-transfer flavoprotein] = a short-chain (2E)-enoyl-CoA + reduced [electron-transfer flavoprotein] butanoyl-CoA + H(+) + oxidized [electron-transfer flavoprotein] = (2E)-butenoyl-CoA + reduced [electron-transfer flavoprotein] H(+) + oxidized [electron-transfer flavoprotein] + pentanoyl-CoA = (2E)-pentenoyl-CoA + reduced [electron-transfer flavoprotein] H(+) + hexanoyl-CoA + oxidized [electron-transfer flavoprotein] = (2E)-hexenoyl-CoA + reduced [electron-transfer flavoprotein] Binds 1 FAD per subunit. Optimum pH is 7.1. Lipid metabolism; mitochondrial fatty acid beta-oxidation. Homotetramer. Belongs to the acyl-CoA dehydrogenase family.