Schematic of one-carbon cycle showing the connection between folate
metabolism and methionine cycle (Scheme adapted from ref (21). Copyright Elsevier 2013).
Color coding: purple, C1 donors; green, folates; blue, products of
C1 metabolism and downstream pathways; white, not covered by method.
Abbreviations: CTH, cystathionine γ-lyase; CBS, cystathionine
β-synthase; DHF, dihydrofolate; FA, folic acid; Hcy, homocysteine;
MAT, methionine adenosyltransferase; MS, methionine synthase; MTHFR,
methylenetetrahydrofolate reductase; 5-MTHF, 5-methyl-tetrahydrofolate;
MT, methyltransferase; SAH, S-adenosylhomocysteine; SAHH, SAH hydrolase;
SAM, S-adenosylmethionine; SHMT, serine hydroxymethyltransferase;
THF, tetrahydrofolate; B6, vitamin B6; B12, vitamin B12.