What happens to SAM after giving its methyl group?
It is converted to s-adenosylhomocysteine (SAH). In order to continue the methylation process and excrete arsenic, SAM must be regenerated. It is obvious that in the event the SAH does not convert back to SAM, the effective removal of arsenic from the body cannot continue for long. The SAH converts to homocysteine which in turns adds a methyl group supplied by 5-methylene tetrahydrofolate (MTHF) in presence of Vitamin B12. By gaining the methyl group homocysteine converts to methionine. Finally methionine converts back to SAM in presence of specific enzyme (SAM synthase). The regenerated SAM can continue detoxifying arsenic or any toxin in the body. Two important points must be mentioned here. First, the MTHF, folates, Vitamin B12 are supplied through food (fresh green leafy vegetables, fruits) or supplements. Methionine is furnished through consumption of protein rich food (chicken meat, egg). Is it any surprising that we constantly hear good nutrition can combat arsenic poisoning. Ho
