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Remethylation
Remethylation involves methylation that occurs in some biochemical cycles. Often methyl groups are not mobile when attached to nitrogen and sulfur, but the removal and reinstallation of methyl groups does occur with the assistance of certain enzymes. Homocysteine-methionine interconversion Remethylation is a major step in the conversion of homocysteine to the essential amino acid methionine. The remethylation process involves the enzyme methionine synthase (MS), which requires Vitamin B12, vitamin B12 as a cofactor, and also depends indirectly on folate and other B vitamins. A second pathway, which is usually restricted to liver and kidney in most mammals, involves betaine-homocysteine methyltransferase, betaine-homocysteine methyltransferase (BHMT) and requires trimethylglycine as a cofactor. DNA processing and epigenetics Remethylation also has a role in epigenetics and neuroplasticity. DNA methylation patterns are largely erased and then re-established (remethylated) between ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methylation
Methylation, in the chemistry, chemical sciences, is the addition of a methyl group on a substrate (chemistry), substrate, or the substitution of an atom (or group) by a methyl group. Methylation is a form of alkylation, with a methyl group replacing a hydrogen#Compounds, hydrogen atom. These terms are commonly used in chemistry, biochemistry, soil science, and biology. In biological systems, methylation is Catalysis, catalyzed by enzymes; such methylation can be involved in modification of heavy metals, regulation of gene expression, regulation of Protein#Functions, protein function, and RNA processing. ''In vitro'' methylation of tissue samples is also a way to reduce some histology#Histological Artifacts, histological staining artifacts. The reverse of methylation is demethylation. In biology In biological systems, methylation is accomplished by enzymes. Methylation can modify heavy metals and can regulate gene expression, RNA processing, and protein function. It is a key pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
