1. One-Carbon Metabolism Derivatives of tetrahydrofolate Derivatives of methionine Vitamin B12 Betaine

2. H H H H Tetrahydrofolate (THF) OH H2NH2N CH 2 H Pteridine p-Aminobenzoic Acid (PABA) Glutamate FOLIC ACID Folate + NADPH + H + 7,8 Dihydrofolate + NADP + 7,8 Dihydrofolate + NADPH + H + Tetrahydrofolate + NADP + Dihydrofolate Reductase

3. N CH 2 N H.. H Uncharged H N CH 2 N H C O 5-Formyl-THF 5 10 N CH 2 N CH 5,10 Methenyl-THF N CH 2 N NADPH H2CH2C 5,10-Methylene-THF N CH 2 N CH 3 5-Methyl-THF NADH SerineGlycine ATP

4. COO H 3 N-C-H CH 2 OH N CH 2 N H H2CH2C 5,10-Methylene-THF SerineGlycine Serine is the main contributor of carbons to the one-carbon pool

5. Formylation Reaction using 10-Formyl-THF

6. Methyl Transfer Reactions COO - H 3 N-C-H CH 2 S CH 3 CH 2 + Methionine ATP S-adenosylmethionine (SAM) Active methyl group PiPi PP i (AdoMet) or +

7. 3 AdoMet Phosphatidylethanolamine Phosphatidylcholine 3 S-adenosylhomocysteine

8. Synthesis of Epinephrine requires SAM or AdoMet

9. Methyl Cycle Methionine S-Adenosylmethionine S-AdenosylhomocysteineHomocysteine 5 Methyl-THF Methyl-B12 Methyl group acceptor Adenosine (SAH) One-carbon Pool ATP