S-Adenosyl-L-homocysteine
S-Adenosyl-L-homocysteine (SAH) is the biosynthetic precursor to homocysteine.[1] SAH is formed by the demethylation of S-adenosyl-L-methionine.[2][3] Adenosylhomocysteinase converts SAH into homocysteine and adenosine.
Biological role[edit]
DNA methyltransferases are inhibited by SAH.[4] Two S-adenosyl-L-homocysteine cofactor products can bind the active site of DNA methyltransferase 3B and prevent the DNA duplex from binding to the active site, which inhibits DNA methylation.[5]