The S-adenosylmethionine (SAM) cycle is a series of metabolic steps that produce, break down, and regenerate S-adenosylmethionine.[1][2][3] The SAM cycle converts S-adenosylmethionine to S-adenosylhomocysteine to homocysteine to methionine and back to S-adenosylmethionine using various enzymes.[1][2][3] The enzymatic conversion of homocysteine to methionine in the SAM cycle uses vitamin B12 as a cofactor and links the SAM cycle to the folate cycle to make up a complex series of metabolic pathways known as one-carbon metabolism.[4] It is called one-carbon metabolism because these processes produce and provide one-carbon methyl groups (CH3) for several important biological processes (DNA synthesis, DNA methylation, immune function, amino acid metabolism, etc.).[1][2][3][4]
References
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- ^Fontecave M, Atta M, Mulliez ES-adenosylmethionine: nothing goes to waste.Trends Biochem Sci.(2004 May)
- ^Mato JM, Alvarez L, Ortiz P, Pajares MAS-adenosylmethionine synthesis: molecular mechanisms and clinical implications.Pharmacol Ther.(1997)
- ^Clare CE, Brassington AH, Kwong WY, Sinclair KDOne-Carbon Metabolism: Linking Nutritional Biochemistry to Epigenetic Programming of Long-Term Development.Annu Rev Anim Biosci.(2019-Feb-15)