S-adenosylmethionine: nothing goes to waste.
S-adenosylmethionine (SAM or AdoMet) is a biological sulfonium compound known as the major biological methyl donor in reactions catalyzed by methyltransferases. SAM is also used as a source of methylene groups (in the synthesis of cyclopropyl fatty acids), amino groups (in the synthesis of 7,8-diaminoperlagonic acid, a precursor of biotin), ribosyl groups (in the synthesis of epoxyqueuosine, a modified nucleoside in tRNAs) and aminopropyl groups (in the synthesis of ethylene and polyamines). Even though the mechanism of most of these reactions has not been extensively characterized, it is likely that the chemistry at work is mainly driven by the electrophilic character of the carbon centers that are adjacent to the positively charged sulfur atom of SAM. In addition, SAM, upon one-electron reduction, is a source of 5'-deoxyadenosyl radicals, which initiate many metabolic reactions and biosynthetic pathways by hydrogen-atom abstraction. SAM presents a unique situation in which all constituent parts have a chemical use.
Fontecave
Marc
M
Laboratoire de Chimie et Biochimie des Centres Rédox Biologiques, UMR no. 5047, Université Joseph Fourier, Département Réponse et Dynamique Cellulaires, CEA/CNRS Grenoble, 17 avenue des Martyrs, 38054 Grenoble Cedex 09, France. mfontecave@cea.fr
Atta
Mohamed
M
Mulliez
Etienne
E
D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000096:biosynthesis; D000123:Acetyltransferases / Q000378:metabolism; D000598:Amino Acids, Cyclic / Q000096:biosynthesis; D000599:Amino Acids, Diamino / Q000096:biosynthesis; D000818:Animals; D003521:Cyclopropanes; D005227:Fatty Acids / Q000096:biosynthesis; D006801:Humans; D019751:Intramolecular Transferases / Q000378:metabolism; D008956:Models, Chemical; D009704:Nucleoside Q / Q000096:biosynthesis; D012264:Ribonucleotide Reductases / Q000378:metabolism; D012436:S-Adenosylmethionine / Q000378:metabolism*; D013095:Spermidine / Q000096:biosynthesis; D014529:Uridine / Q000031:analogs & derivatives* / Q000096:biosynthesis
D000598:Amino Acids, Cyclic; D000599:Amino Acids, Diamino; D003521:Cyclopropanes; D005227:Fatty Acids; C028775:cyclopropane fatty acids; C088386:homoserine lactone; C004720:7,8-diaminopelargonic acid; C023863:1-aminocyclopropane-1-carboxylic acid; C006514:3-(3-amino-3-carboxypropyl)uridine; D009704:Nucleoside Q; D012436:S-Adenosylmethionine; D012264:Ribonucleotide Reductases; D000123:Acetyltransferases; C022560:formate C-acetyltransferase; D019751:Intramolecular Transferases; C021518:lysine 2,3-aminomutase; D015107:4-Butyrolactone; D013095:Spermidine; D014529:Uridine