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.

S-Adenosyl-L-homocysteine
Names
IUPAC name
S-(5′-Deoxyadenos-5′-yl)-L-homocysteine
Systematic IUPAC name
(2S)-2-Amino-4-({[(2S,3S,4R,5R)-5-(6-amino-9H-purin-9-yl)-3,4-dihydroxyoxolan-2-yl]methyl}sulfanyl)butanoic acid
Other names
AdoHcy, 2-S-adenosyl-L-homocysteine,
5′-S-(3-Amino-3-carboxypropyl)-5′-thioadenosine S-adenosylhomocysteine, SAH
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.012.328
KEGG
MeSH S-Adenosylhomocysteine
UNII
  • InChI=1S/C14H20N6O5S/c15-6(14(23)24)1-2-26-3-7-9(21)10(22)13(25-7)20-5-19-8-11(16)17-4-18-12(8)20/h4-7,9-10,13,21-22H,1-3,15H2,(H,23,24)(H2,16,17,18)/t6-,7+,9+,10+,13+/m0/s1 checkY
    Key: ZJUKTBDSGOFHSH-WFMPWKQPSA-N checkY
  • InChI=1/C14H20N6O5S/c15-6(14(23)24)1-2-26-3-7-9(21)10(22)13(25-7)20-5-19-8-11(16)17-4-18-12(8)20/h4-7,9-10,13,21-22H,1-3,15H2,(H,23,24)(H2,16,17,18)/t6-,7+,9+,10+,13+/m0/s1
    Key: ZJUKTBDSGOFHSH-WFMPWKQPBX
  • O=C(O)[C@@H](N)CCSC[C@H]3O[C@@H](n2cnc1c(ncnc12)N)[C@H](O)[C@@H]3O
Properties
C14H20N6O5S
Molar mass 384.41 g·mol−1
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Biological role

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]

References
  1. Finkelstein JD (2000). "Pathways and regulation of homocysteine metabolism in mammals". Seminars in Thrombosis and Hemostasis. 26 (3): 219–225. doi:10.1055/s-2000-8466. PMID 11011839.
  2. Ribbe MW, Hu Y, Hodgson KO, Hedman B (April 2014). "Biosynthesis of nitrogenase metalloclusters". Chemical Reviews. 114 (8): 4063–4080. doi:10.1021/cr400463x. PMC 3999185. PMID 24328215.
  3. James SJ, Melnyk S, Pogribna M, Pogribny IP, Caudill MA (August 2002). "Elevation in S-adenosylhomocysteine and DNA hypomethylation: potential epigenetic mechanism for homocysteine-related pathology". The Journal of Nutrition. 132 (8 Suppl): 2361S–2366S. doi:10.1093/jn/132.8.2361S. PMID 12163693.
  4. Kumar R, Srivastava R, Singh RK, Surolia A, Rao DN (March 2008). "Activation and inhibition of DNA methyltransferases by S-adenosyl-L-homocysteine analogues". Bioorganic & Medicinal Chemistry. 16 (5): 2276–2285. doi:10.1016/j.bmc.2007.11.075. PMID 18083524.
  5. Lin CC, Chen YP, Yang WZ, Shen JC, Yuan HS (April 2020). "Structural insights into CpG-specific DNA methylation by human DNA methyltransferase 3B". Nucleic Acids Research. 48 (7): 3949–3961. doi:10.1093/nar/gkaa111. PMC 7144912. PMID 32083663.
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