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One-Carbon Metabolism. Derivatives of tetrahydrofolate Derivatives of methionine Vitamin B12 Betaine. H. CH 2. OH. H 2 N. H. H. H. H. FOLIC ACID. p -Aminobenzoic Acid (PABA). Pteridine. Tetrahydrofolate (THF). Glutamate. Folate + NADPH + H +. 7,8 Dihydrofolate + NADP +.
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One-Carbon Metabolism • Derivatives of tetrahydrofolate • Derivatives of methionine • Vitamin B12 • Betaine
H CH2 OH H2N H H H H FOLIC ACID p-Aminobenzoic Acid (PABA) Pteridine Tetrahydrofolate (THF) Glutamate Folate + NADPH + H+ 7,8 Dihydrofolate + NADP+ Dihydrofolate Reductase Tetrahydrofolate + NADP+ 7,8 Dihydrofolate + NADPH + H+
N N N N CH2 CH2 CH2 CH2 C N N N N N .. CH2 H C O H H H N H H2C 5 ATP 10 5,10 Methenyl-THF Uncharged 5-Formyl-THF NADPH NADH CH3 5-Methyl-THF 5,10-Methylene-THF Serine Glycine
N CH2 COO N H3N-C-H CH2OH H H2C 5,10-Methylene-THF Glycine Serine Serine is the main contributor of carbons to the one-carbon pool
COO- + H3N-C-H CH2 CH2 + S CH3 Active methyl group Methyl Transfer Reactions ATP Pi PPi Methionine S-adenosylmethionine (SAM) or (AdoMet)
3 S-adenosylhomocysteine Phosphatidylethanolamine 3 AdoMet Phosphatidylcholine
Synthesis of Epinephrine requires SAM or AdoMet
ATP Methyl Cycle Methionine S-Adenosylmethionine Methyl-B12 Methyl group acceptor Homocysteine S-Adenosylhomocysteine (SAH) 5 Methyl-THF One-carbon Pool Adenosine