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S-Adenosylmethionine

  1. George D Markham

Published Online: 19 APR 2010

DOI: 10.1002/9780470015902.a0000662.pub2

eLS

eLS

How to Cite

Markham, G. D. 2010. S-Adenosylmethionine. eLS. .

Author Information

  1. The Institute for Cancer Research, Fox Chase Cancer Center, Philadelphia, Pennsylvania, USA

Publication History

  1. Published Online: 19 APR 2010

Abstract

S-adenosylmethionine is one of the few sulfonium ions found in nature and it plays essential roles in the metabolism of all known organisms. The positively charged sulfonium centre endows S-adenosylmethionine with a chemical versatility matched by few other biochemicals, perhaps exceeding even adenosine triphosphate (ATP). S-adenosylmethionine is used in a multitude of metabolic pathways, and the types of chemical reactions in which it partakes are highly varied, ranging from alkylation to free-radical formation. S-sdenosylmethionine is methyl donor in many biosynthetic reactions, whereas methylation of both deoxyribonucleic acid(DNA) and proteins is part of the epigenetic control of cell growth and development. In other pathways, the propylamine moiety is incorporated into the pervasive polyamines spermidine and spermine. Unusual reactions consume S-adenosylmethionine in the formation of plant growth factor ethylene, of cyclopropane fatty acids and in sulfur insertion in the biosynthesis of biotin, lipoic acid and thiamine. S-adenosylmethionine appears to be one of the molecules required for life.

Key concepts:

  • S-adenosylmethionine is a branch point compound with components from purine, amino acid and reduced sulfur metabolism, and thus is potentially able to coordinate these three areas of metabolism. S-adenosylmethionine appears to be required for life.

  • The sulfonium centre of S-adenosylmethionine is able to transfer any of the three attached alkyl groups, providing a metabolic versatility matched by few other biological molecules.

  • S-adenosylmethionine is a progenitor of free radicals that occur as protein-bound reaction intermediates in unusual chemical transformations catalysed by the ‘Radical SAM’: family of enzymes.

  • S-adenosylmethionine metabolism is commonly disrupted in liver disease, and hereditary defects have been found in a few patients with abnormal sulfur metabolism.

  • S-adenosylmethionine is under investigation as a potential drug in treatment of depression, arthritis and liver disease.

Keywords:

  • coenzymes and cofactors;
  • methylation;
  • free radicals;
  • nucleosides;
  • quorum sensing;
  • polyamines