preferred_name: (6S)-5,6,7,8-tetrahydrofolyl-(gamma-L-Glu)(n) + N,N-dimethylglycine + oxidized [electron-transfer flavoprotein] + H(+) <=> (6R)-5,10-methylenetetrahydrofolyl-(gamma-L-Glu)(n) + sarcosine + reduced [electron-transfer flavoprotein]