(2S)-methylsuccinyl-CoA + oxidized [electron-transfer flavoprotein] + H(+) => 2-methylfumaryl-CoA + reduced [electron-transfer flavoprotein]
(2s)-methylsuccinyl-coa + oxidized [electron-transfer flavoprotein] + h(+) => 2-methylfumaryl-coa + reduced [electron-transfer flavoprotein]
(2S)-methylsuccinyl-CoA + oxidized [electron-transfer flavoprotein] + H(+) => 2-methylfumaryl-CoA + reduced [electron-transfer flavoprotein]
(2s)-methylsuccinyl-coa + oxidized [electron-transfer flavoprotein] + h(+) => 2-methylfumaryl-coa + reduced [electron-transfer flavoprotein]