3543174 MTHFR methylenetetrahydrofolate reductase 4730 3087295 MTHF 2-methyltetrahydrofuran 109 3087292 mTHF 5,10-methylenetetrahydrofolate 11 3710773 methyleneTHF 5,10-methylenetetrahydrofolate 8 3966646 5,10-MTHF 5,10-methylenetetrahydrofolate 4 2032034 5,10-MeTHF 5,10-methenyl-tetrahydrofolate 2 2157458 5,10-methenylTHF 5,10-methylenetetrahydrofolate 2 2078302 methyl donor 5,10-methylenetetrahydrofolate 1