thioether S-methyltransferase activity

Definition

Target type: molecularfunction

Catalysis of the reaction: S-adenosyl-L-methionine(1+) + dimethyl sulfide = S-adenosyl-L-homocysteine + trimethylsulfonium. [EC:2.1.1.96, RHEA:19613]

Thioether S-methyltransferase activity is a fundamental enzymatic process involved in the transfer of a methyl group from a donor molecule, typically S-adenosyl methionine (SAM), to a sulfur atom within a thioether moiety. This methylation reaction plays crucial roles in a wide range of cellular processes, including:

* **Metabolic Pathways:** Thioether S-methyltransferases are involved in the biosynthesis of essential biomolecules like coenzyme M (CoM) in methanogenesis, the production of the neurotransmitter melatonin, and the synthesis of the amino acid methionine.

* **Detoxification:** These enzymes participate in the detoxification of xenobiotics and environmental pollutants, by modifying their chemical structure and facilitating their elimination from the body.

* **Gene Regulation:** Thioether S-methyltransferases are involved in regulating gene expression by modifying proteins that bind to DNA, influencing the accessibility of genes for transcription.

* **Cellular Signaling:** Some thioether S-methyltransferases regulate cellular signaling pathways by modifying proteins involved in signal transduction, affecting the downstream responses to stimuli.

The catalytic mechanism of thioether S-methyltransferases typically involves a two-step process:

1. **Formation of a transient covalent intermediate:** The enzyme first interacts with SAM and facilitates the transfer of the methyl group to a cysteine residue in the active site. This creates a temporary covalent linkage between the enzyme and the methyl group.

2. **Transfer of the methyl group to the substrate:** The activated methyl group is then transferred from the enzyme to the sulfur atom of the thioether substrate. This reaction results in the formation of a methylated thioether and regenerates the free enzyme.

The specificity of thioether S-methyltransferases for their substrates is determined by the unique three-dimensional structure of the enzyme's active site. This site provides specific interactions with both the donor molecule (SAM) and the thioether substrate, ensuring accurate and efficient methyl transfer.

Understanding the molecular function of thioether S-methyltransferases is crucial for elucidating their role in various biological processes, and for developing potential therapeutic strategies targeting these enzymes in disease states.'
"

Proteins (1)

Compounds (4)