SAMe S-Adenosyl-l-methiononine

SAMe from AOR
S-Adenosyl-l-methiononine, or SAMe, is a naturally-occurring physiological agent in the human body that forms an integral part of the methylation cycle. It is formed in the body through the combination of the amino acid methionine and adenosine triphosphate (ATP). This compound was first isolated in Italy in 1952 and is now a prescription drug in much of Europe, most commonly it seems, as an anti-depressant. Safe, energizing, and purported to treat depression twice as fast as standard anti-depressants such as Prozac^TM, SAMe has become more popular than the latter in the nation of its discovery, in spite of being more expensive there. SAMe is also heavily studied for its ability to alleviate the conditions of osteoarthritis as well as to treat liver disease.

Biochemical Mechanism of Action for the Methylation Cycle
SAMe, which is found in every living cell, begins with the essential amino acid methionine. Methionine then binds with adenosine triphosphate (ATP) to create SAMe. SAMe's creation is immediately followed by the donation of its methyl group (comprised of the 4 atoms at the tail end of the original amino acid methionine) to another molecule called a methyl acceptor. After SAMe has imparted its methyl donor it is converted to SAH, or S-Adenosylhomocysteine, which is rapidly broken down to form homocysteine. This is a potentially dangerous situation as homocysteine is essentially metabolic waste which can be toxic. Fortunately, it only exists as an intermediary product to be broken down by the B-complex vitamins, especially B6, B12, and folic acid. B6 breaks homocysteine down to cysteine, which in turn binds with glutamic acid and glycine to form glutathione. Vitamins B12 and folic acid for their parts convert homocysteine back into methionine, thus ending (and re-starting, or remethylating) the methylation cycle.

 SAMe and Depression

It is as an anti-depressant that SAMe seems to have established itself in the collective mindset of the scientific community. At first glance, this sounds like a scientific stretch when the aforementioned biochemical functions of SAMe are re-examined. However, as was previously noted, the influence of the methylation cycle is so widespread that it affects factors of the central nervous system that are directly pertinent to depression.