Demethylation

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BBr3demethylation

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Demethylation is a biochemical process involving the removal of a methyl group (CH₃) from a molecule. This process is crucial in the regulation of gene expression, protein function, and cellular signaling.

Mechanism

Demethylation can occur through various mechanisms, including:

• Oxidative demethylation: This involves the oxidation of the methyl group, often mediated by enzymes such as cytochrome P450.
• Hydrolytic demethylation: This involves the addition of a water molecule to break the bond between the methyl group and the rest of the molecule.
• Enzymatic demethylation: Specific enzymes, such as DNA demethylase and histone demethylase, catalyze the removal of methyl groups from DNA and histones, respectively.

Biological Significance

Demethylation plays a critical role in various biological processes, including:

• Gene expression: Demethylation of DNA and histones can activate or repress gene expression. For example, the demethylation of CpG islands in gene promoters is often associated with gene activation.
• Epigenetic regulation: Demethylation is a key mechanism in epigenetics, influencing cell differentiation, development, and disease.
• Protein function: Demethylation of proteins can alter their function, stability, and interactions with other molecules.

Enzymes Involved

Several enzymes are involved in demethylation, including:

• TET enzymes: These enzymes oxidize 5-methylcytosine in DNA to facilitate its removal.
• LSD1 (lysine-specific demethylase 1): This enzyme demethylates histones, affecting chromatin structure and gene expression.
• JmjC domain-containing proteins: These are a family of histone demethylases that require Fe(II) and α-ketoglutarate for their activity.

Clinical Relevance

Aberrant demethylation is associated with various diseases, including:

• Cancer: Abnormal DNA demethylation can lead to the activation of oncogenes or the silencing of tumor suppressor genes.
• Neurological disorders: Dysregulation of demethylation processes is implicated in conditions such as Alzheimer's disease and schizophrenia.
• Autoimmune diseases: Altered demethylation patterns can contribute to the pathogenesis of diseases like systemic lupus erythematosus.

Related Pages

• Methylation
• Epigenetics
• Gene expression
• Histone modification
• DNA methylation

See Also

• CpG island
• Epigenome
• Chromatin
• Transcription factors

External Links

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