What is the Origin of S-Adenosylmethionine Cycle?

This fundamental pathway was first elucidated in the mid-20th century as biochemists mapped the flow of one-carbon units in cellular metabolism. The cycle's importance has been further highlighted in modern clinical practice with the understanding of its role in epigenetics and the impact of B vitamin status. It is a cornerstone of understanding nutritional biochemistry and its clinical consequences.

What is the Mechanism of S-Adenosylmethionine Cycle?

The cycle begins with the synthesis of SAMe from the amino acid methionine, a reaction requiring ATP and the enzyme methionine adenosyltransferase. SAMe then transfers its methyl group to a recipient molecule, becoming S-Adenosylhomocysteine (SAH). SAH is subsequently converted to homocysteine, which is then recycled back to methionine, often requiring methylfolate and vitamin B12 as cofactors, thereby completing the cycle. The efficiency of this mechanism dictates the body's ability to execute critical regulatory functions.

S-Adenosylmethionine Cycle ∞ Area

S-Adenosylmethionine Cycle

Meaning

The S-Adenosylmethionine Cycle, often referred to as the SAMe cycle, is a central biochemical pathway in human metabolism responsible for generating, utilizing, and regenerating the universal methyl donor molecule, S-Adenosylmethionine (SAMe). This cycle is crucial because SAMe is required for over 100 methylation reactions, which are essential for gene regulation, neurotransmitter synthesis, hormone metabolism, and detoxification.