NationMaster - Encyclopedia: Methylation

Methylation is a term used in the chemical sciences to denote the attachment or substitution of a methyl group on various substrates. This term is commonly used in chemistry, biochemistry, and the biological sciences. In chemistry a methyl-group is a hydrophobic Alkyl functional group which is derived from methane (CH4). ... For other uses, see Substrate. ... Biochemistry is the study of the chemical processes and transformations in living organisms. ...

In biochemistry, methylation more specifically refers to the replacement of a hydrogen atom with the methyl group. General Name, Symbol, Number hydrogen, H, 1 Chemical series nonmetals Group, Period, Block 1, 1, s Appearance colorless Atomic mass 1. ...

In biological systems, methylation is catalyzed by enzymes; such methylation can be involved in modification of heavy metals, regulation of gene expression, regulation of protein function, and RNA metabolism. Methylation of heavy metals can also occur outside of biological systems. Chemical methylation of tissue samples is also one method for reducing certain histological staining artifacts. In chemistry and biology, catalysis is the acceleration (increase in rate) of a chemical reaction by means of a substance, called a catalyst, that is itself not consumed by the overall reaction. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... A heavy metal is any of a number of higher atomic weight elements, which has the properties of a metallic substance at room temperature. ... Gene expression, or simply expression, is the process by which a genes DNA sequence is converted into the structures and functions of a cell. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... A heavy metal is any of a number of higher atomic weight elements, which has the properties of a metallic substance at room temperature. ... For other uses, see Life (disambiguation), Lives (disambiguation) or Living (disambiguation), Living Things (disambiguation) Look up life, living in Wiktionary, the free dictionary. ... A thin section of lung tissue stained with hematoxylin and eosin. ...

Biological methylation

Epigenetics

Methylation contributing to epigenetic inheritance can occur either through DNA methylation or protein methylation. It has been suggested that this article or section be merged with Epigenetics. ...

DNA methylation in vertebrates typically occurs at CpG sites (cytosine-phosphate-guanine sites; that is, where a cytosine is directly followed by a guanine in the DNA sequence); this methylation results in the conversion of the cytosine to 5-methylcytosine. The formation of Me-CpG is catalyzed by the enzyme DNA methyltransferase. CpG sites are uncommon in vertebrate genomes but are often found at higher density near vertebrate gene promoters where they are collectively referred to as CpG islands. The methylation state of these CpG sites can have a major impact on gene activity/expression. DNA methylation is a type of chemical modification of DNA that can be inherited without changing the DNA sequence. ... CpG sites are regions of the DNA where a cytosine nucleotide is situated next to a guanine nucleotide. ... Cytosine is one of the 5 main nucleobases used in storing and transporting genetic information within a cell in the nucleic acids DNA and RNA. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached (an amine group at position 4 and a keto group at... Guanine is one of the five main nucleobases found in the nucleic acids DNA and RNA; the others being adenine, cytosine, thymine, and uracil. ... 5-methylcytosine is the methylated form of cytosine. ... In chemistry and biology, catalysis is the acceleration (increase in rate) of a chemical reaction by means of a substance, called a catalyst, that is itself not consumed by the overall reaction. ... Ribbon diagram of the enzyme TIM, surrounded by the space-filling model of the protein. ... DNA methyltransferase is an enzyme whose function is to catalyze the transfer of methyl groups between molecules, in this case, DNA. There are two main types of methyltransferases, de novo and maintenance. ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... For other meanings of this term, see gene (disambiguation). ... A promoter is a DNA sequence that contains the information, in the form of DNA sequences, that permits the proper activation or repression of the gene which it controls, i. ... CpG islands are regions of DNA near and in the promoter of a mammalian gene where a large concentration of phosphodiester-linked cytosine and guanine pairs exist. ... Gene expression, or simply expression, is the process by which a genes DNA sequence is converted into the structures and functions of a cell. ...

Protein methylation typically takes place on arginine or lysine amino acid residues in the protein sequence. Arginine can be methylated once (monomethylated arginine) or twice, with either both methyl groups on one terminal nitrogen (asymmetric dimethylated arginine) or one on both nitrogens (symmetric dimethylated arginine) by peptidylarginine methyltransferases (PRMTs). Lysine can be methylated once, twice or three times by lysine methyltransferases. Protein methylation has been most well studied in the histones. The transfer of methyl groups from S-adenosyl methionine to histones is catalyzed by enzymes known as histone methyltransferases. Histones which are methylated on certain residues can act epigenetically to repress or activate "gene" expression. Protein methylation is one type of post-translational modification. Arginine (symbol Arg or R) is an Î±-amino acid. ... Lysine is one of the 20 amino acids normally found in proteins. ... Phenylalanine is one of the standard amino acids. ... Schematic representation of the assembly of the core histones into the nucleosome. ... In chemistry a methyl-group is a hydrophobic Alkyl functional group which is derived from methane (CH4). ... This article does not cite its references or sources. ... Histone methyltransferases (HMT) are enzymes which catalyze the transfer of one to three methyl groups from the cofactor s-adenosylmethionine to lysine and arginine residues of histone proteins. ... In Biology, while the subject of genetics focuses on how organisms can inherit traits by inheriting genes from their parent(s), which encode information for cell function as sequences of DNA, epigenetics is sometimes used to refer to additional methods of biological inheritance that do not directly relate to the... Posttranslational modification means the chemical modification of a protein after its translation. ...

Embryonic development

In early development (fertilization to 8-cell stage), the eukaryotic genome is demethylated. From the 8-cell stage to the morula, de novo methylation of the genome occurs, modifying and adding epigenetic information to the genome. By blastula stage, the methylation is complete. This process is referred to as "epigenetic reprogramming". The importance of methylation was shown in knockout mutants without DNA methyltransferase. All the resulting embryos died at the morula stage. Categories: Biology stubs ... The 8-cell stage is a period in embryonic development when the conceptus has undergone 3 cleavages from a single cell, resulting in 8 cells. ... Demethylation is the chemical process resulting in the removal a methyl group (CH3) from a molecule. ... Morula is a stage of embryonic development in animals, including the 16-cell phase, the 32-cell phase, and the 64-cell phase. ... Blastulation. ... A gene knockout is a genetically engineered organism that carries one or more genes in its chromosomes that has been made inoperative. ... It has been suggested that embryology be merged into this article or section. ...

Methylation in postnatal development

Increasing evidence is revealing a role of methylation in the interaction of environmental factors with genetic expression. Differences in maternal care during the first 6 days of life in the rat induce differential methylation patterns in some promoter regions and thus influencing gene expression (Weaver IC, et al (Aug 2004; epub Jun 27 2004). "Epigenetic programming by maternal behavior.". Nature Neuroscience 7(8): 791-92. ). Furthermore, even more dynamic processes such as interleukin signaling have been shown to be regulated by methylation (Bird A. (Mar 2003). "Il2 transcription unleashed by active DNA demethylation.". Nature Immunology 4(3): 208-9. ). Species 50 species; see text *Several subfamilies of Muroids include animals called rats. ... A promoter is a DNA sequence that contains the information, in the form of DNA sequences, that permits the proper activation or repression of the gene which it controls, i. ... Gene expression, or simply expression, is the process by which a genes DNA sequence is converted into the structures and functions of a cell. ... Interleukins are a group of cytokines that were first seen to be expressed by white blood cells (leukocytes, hence the -leukin) as a means of communication (inter-). The name is sort of a relic though; it has since been found that interleukins are produced by a wide variety of bodily...

Methylation and cancer

The pattern of methylation has recently become an important topic for research. Studies have found that in normal tissue, methylation of a gene is mainly localised to the coding region, which is CpG poor. In contrast, the promoter region of the gene is unmethylated, despite a high density of CpG islands in the region. The coding region of a gene is the portion of DNA that is transcribed into mRNA and translated into proteins. ...

Neoplasia is characterized by "methylation imbalance" where genome-wide hypomethylation is accompanied by localized hypermethylation and an increase in expression of DNA methyltransferase (1). The overall methylation state in a cell might also be a precipitating factor in carcinogenesis as evidence suggests that genome-wide hypomethylation can lead to chromosome instability and increased mutation rates (3). The methylation state of some genes can be used as a biomarker for tumorigenesis. For instance, hypermethylation of the pi-class glutathione S-transferase gene (GSTP1) appears to be a promising diagnostic indicator of prostate cancer (2). Neoplasia (new growth in Greek) is abnormal, disorganized growth in a tissue or organ, usually forming a distinct mass. ... In biology the genome of an organism is the whole hereditary information of an organism that is encoded in the DNA (or, for some viruses, RNA). ... Gene expression, or simply expression, is the process by which a genes DNA sequence is converted into the structures and functions of a cell. ... DNA methyltransferase is an enzyme whose function is to catalyze the transfer of methyl groups between molecules, in this case, DNA. There are two main types of methyltransferases, de novo and maintenance. ... Prostate cancer is a disease in which cancer develops in the prostate, a gland in the male reproductive system. ...

In cancer, the dynamics of genetic and epigenetic gene silencing are very different. Somatic genetic mutation leads to a block in the production of functional protein from the mutant allele. If a selective advantage is conferred to the cell, the cells expand clonally to give rise to a tumor in which all cells lack the capacity to produce protein. In contrast, epigenetically mediated gene silencing occurs gradually. It begins with a subtle decrease in transcription, fostering a decrease in protection of the CpG island from the spread of flanking heterochromatin and methylation into the island. This loss results in gradual increases of individual CpG sites, which vary between copies of the same gene in different cells (6).

Methylation and bacterial host defense

Additionally, adenosine or cytosine methylation is part of the restriction modification system of many bacteria. Bacterial DNAs are methylated periodically throughout the genome. A Methylase is the enzyme that recognizes a specific sequence and methylates one of the bases in or near that sequence. Foreign DNAs (which are not methylated in this manner) that are introduced into the cell are degraded by restriction enzymes. This acts as a sort of primitive immune system, allowing the bacteria to protect themselves from infection by bacteriophage or phage. This type of methylation is the basis of restriction fragment length polymorphism (RFLP) testing. With this technique, geneticists use various bacterial restriction endonucleases (restriction enzymes) to split DNA at specific sites in order to detect DNA polymorphisms, useful for genetic fingerprinting and genetic engineering. Adenosine is a nucleoside comprised of adenine attached to a ribose (ribofuranose) moiety via a Î²-N9-glycosidic bond. ... Cytosine is one of the 5 main nucleobases used in storing and transporting genetic information within a cell in the nucleic acids DNA and RNA. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached (an amine group at position 4 and a keto group at... The restriction modification system is used by prokaryotic organisms (i. ... Phyla/Divisions Actinobacteria Aquificae Bacteroidetes/Chlorobi Chlamydiae/Verrucomicrobia Chloroflexi Chrysiogenetes Cyanobacteria Deferribacteres Deinococcus-Thermus Dictyoglomi Fibrobacteres/Acidobacteria Firmicutes Fusobacteria Gemmatimonadetes Nitrospirae Omnibacteria Planctomycetes Proteobacteria Spirochaetes Thermodesulfobacteria Thermomicrobia Thermotogae Bacteria (singular, bacterium) are a major group of living organisms. ... The structure of part of a DNA double helix Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions for the development and function of living organisms. ... Methylase is an enzyme that attaches a methyl group to a molecule, e. ... Drawing of the structure of cork as it appeared under the microscope to Robert Hooke from Micrographia which is the origin of the word cell. Cells in culture, stained for keratin (red) and DNA (green). ... A restriction enzyme (or restriction endonuclease) is an enzyme that cuts double-stranded DNA. The enzyme makes two incisions, one through each of the phosphate backbones of the double helix without damaging the bases. ... A bacteriophage (from bacteria and Greek phagein, to eat) is a virus that infects bacteria. ... This article or section does not cite its references or sources. ... In molecular biology, the term restriction fragment length polymorphism (or RFLP, often pronounced rif-lip) is used in two related contexts: as a characteristic of DNA molecules (arising from their differing nucleotide sequences) by which they may be distinguished, as the laboratory technique which uses this characteristic to compare DNA... Endonucleases are enzymes that cleave the phosphodiester bond within a nucleotide chain. ... In biology, polymorphism can be defined as the occurrence in the same habitat of two or more forms of a trait in such frequencies that the rarer cannot be maintained by recurrent mutation alone. ... This article or section does not adequately cite its references or sources. ... An iconic image of genetic engineering; this autoluminograph from 1986 of a glowing transgenic tobacco plant bearing the luciferase gene, illustrating the possibilities of genetic engineering. ...

Methylation in chemistry

The term methylation in organic chemistry refers to the alkylation process used to describe the delivery of a CH₃ group. This is commonly performed using electrophilic methyl sources - iodomethane, dimethyl sulfate, dimethyl carbonate, or less commonly with the more powerful (and more dangerous) methylating reagents of methyl triflate or methyl fluorosulfonate (magic methyl), which all react via S_N2 nucleophilic substitution. For example a carboxylate may be methylated pm pxygen to give a methyl ester, an alkoxide salt RO⁻ may be likewise methylated to give an ether, ROCH₃, or a ketone enolate may be methylated on carbon to produce a new ketone. Organic chemistry is a specific discipline within chemistry which involves the scientific study of the structure, properties, composition, reactions, and preparation (by synthesis or by other means) of chemical compounds consisting of primarily carbon and hydrogen, which may contain any number of other elements, including nitrogen, oxygen, halogens as well... Alkylation is the transfer of an alkyl group from one molecule to another. ... In chemistry, an electrophile (literally electron-lover) is a reagent attracted to electrons that participates in a chemical reaction by accepting an electron pair in order to bond to a nucleophile. ... Iodomethane, commonly called methyl iodide, is a dense volatile liquid. ... Dimethyl sulfate has chemical formula (CH3)2SO4. ... Dimethyl carbonate, often abbreviated DMC is a flammable clear liquid boiling at 90 Â°C, insoluble in water. ... Methyl trifluoromethanesulfonate, is commonly called methyl triflate, and has the chemical formula CF3SO2-OCH3, and is used as a very powerful (and very dangerous) methylating reagent in chemistry. ... Methyl fluorosulfonate, is commonly called magic methyl, and has the chemical formula F-SO2-OCH3, and is used as a very powerful (and very dangerous) methylating reagent in chemistry. ... In chemistry, nucleophilic substitution is a class of substitution reaction in which an electron-rich nucleophile attacks a molecule and replaces a group or atom, called the leaving group. ... Structure of a carboxylic acid Carboxylic acids, also known as alkanoic acids, are organic acids characterized by the presence of a carboxyl group and have the general chemical formula R-C(=O)-OH, also written as R-COOH, where R is a hydrogen or an alkyl group. ... General formula of a carboxylate ester. ... An alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. ... Ether is the general name for a class of chemical compounds which contain an ether group â€” an oxygen atom connected to two (substituted) alkyl groups. ... Enol (or, more officially, but less commonly: alkenol) is an alkene with hydroxyl group on one of the carbon atoms of the double bond. ... Ketone group A ketone is either the functional group characterized by a carbonyl group linked to two other carbon atoms or a chemical compound that contains this functional group. ...

Alternatively, the methylation may involve use of nucleophilic methyl compounds such as methyllithium (CH₃Li) or Grignard reagents (CH₃MgX). For example, CH₃Li will methylate acetone, adding across the carbonyl (C=O) to give the lithium alkoxide of tert-butanol: In chemistry, a nucleophile (literally nucleus lover) is a reagent which is attracted to centres of positive charge. ... An organolithium reagent is an organometallic compound with a direct bond between a carbon and a lithium atom. ... A Grignard Reagent is an alkyl- or aryl- magnesium halide. ... In chemistry, acetone (also known as propanone, dimethyl ketone, 2-propanone, propan-2-one and Î²-ketopropane) is the simplest representative of the ketones. ... Carbonyl group In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom. ... In chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom. ... An alkoxide is the conjugate base of an alcohol and therefore consists of an organic group bonded to a negatively charged oxygen atom. ... Butanol or butyl alcohol (sometimes also called biobutanol when produced biologically), is an alcohol with a 4 carbon structure and the molecular formula of C4H10O. It is primarily used as a solvent, as an intermediate in chemical synthesis, and as a fuel. ...

Image File history File links Size of this preview: 800 Ã— 428 pixel Image in higher resolution (1249 Ã— 668 pixel, file size: 8 KB, MIME type: image/png) en:Nucleophilic addition by en:methyl lithium on en:acetone. ...

References

External links

Categories: Epigenetics | Chemical reactions | Posttranslational modification | Methylating agents A protein primary structure is a chain of amino acids. ... Posttranslational modification is the chemical modification of a protein after its translation. ... An overview of protein synthesis. ... A peptide bond is a chemical bond formed between two molecules when the carboxyl group of one molecule reacts with the amino group of the other molecule, releasing a molecule of water (H2O). ... Proteolysis is the directed degradation (digestion) of proteins by cellular enzymes called proteases or by intramolecular digestion. ... In chemistry racemization refers to partial conversion of one enantiomer into another. ... The N-terminal end (also known as the N-terminus, N-terminal domain or amine-terminus) refers to the extremity of a protein or polypeptide terminated by an amino acid with a free amine group (-NH2). ... Acetylation describes a reaction, usually with acetic acid, that introduces an acetyl functional group into an organic compound. ... Categories: | | ... This article needs to be wikified. ... Pyroglutamate is an uncommon amino acid found in bacteriorhodopsin. ... Glycation is the result of a sugar-reducing molecule, such as fructose or glucose, bonding to a protein or lipid molecule without the controlling action of an enzyme. ... This article needs to be wikified. ... The C-terminal end refers to the extremity of a protein or polypeptide terminated by an amino acid with a free carboxyl group (COOH). ... Amide functional group In chemistry, an amide is one of two kinds of compounds: the organic functional group characterized by a carbonyl group (C=O) linked to a nitrogen atom (N), or a compound that contains this functional group (pictured to the right); or a particular kind of nitrogen anion. ... A GPI anchor or glycosylphosphatidylinositol is a common posttranslational modification of the C-terminus of membrane-attached proteins. ... // Background Ubiquitylation, also termed ubiquitination, refers to the process particular to eukaryotes whereby a protein is post-translationally modified by covalent attachment of a small protein. ... Small Ubiquitin-related Modifier or SUMO proteins are a family of small proteins that are covalently attached to and detached from other proteins in cells to modify their function. ... Lysine is one of the 20 amino acids normally found in proteins. ... Acetylation describes a reaction, usually with acetic acid, that introduces an acetyl functional group into an organic compound. ... In chemistry, acylation is the process of adding an acyl group to a compound. ... Hydroxylation is any chemical process that introduces one or more hydroxyl groups (-OH) into a compound (or radical) thereby oxidising it. ... Ubiquitin is a very conserved small regulatory protein that is ubiquitous in eukaryotes. ... Small Ubiquitin-related Modifier or SUMO proteins are a family of small proteins that are covalently attached to and detached from other proteins in cells to modify their function. ... This article, image, template or category should belong in one or more categories. ... Deamination is the removal of an amine group from a molecule. ... Oxidative deamination is a form of deamination which generates oxoacids in the liver. ... An imine is a functional group or chemical compound containing a carbon-nitrogen double bond. ... Glycation is the result of a sugar-reducing molecule, such as fructose or glucose, bonding to a protein or lipid molecule without the controlling action of an enzyme. ... Cysteine is a naturally occurring amino acid which has a thiol group and is found in most proteins, though only in small quantities. ... In chemistry, a disulfide bond is a single covalent bond derived from the coupling of thiol groups. ... Prenylation or isoprenylation is the addition of hydrophobic molecules to a protein to facilitate its attachment to the cell membrane. ... Palmitoylation is the covalent attachment of fatty acids to cysteine residues of membrane proteins [1] ^ Linder, M.E. (2000). ... Serine is one of the 20 natural amino acids. ... Threonine is one of the 20 natural amino acids. ... A phosphorylated serine residue Phosphorylation is the addition of a phosphate (PO4) group to a protein or a small molecule or the introduction of a phosphate group into an organic molecule. ... Glycosylation is the process or result of addition of saccharides to proteins and lipids. ... Tyrosine (from the Greek tyros, meaning cheese, as it was first discovered in 1846 by German chemist Justus von Liebig in cheese[1][2]), 4-hydroxyphenylalanine, or 2-amino-3(4-hydroxyphenyl)-propanoic acid, is one of the 20 amino acids that are used by cells to synthesize proteins. ... A phosphorylated serine residue Phosphorylation is the addition of a phosphate (PO4) group to a protein or a small molecule or the introduction of a phosphate group into an organic molecule. ... Tyrosine sulfation is a posttranslational modification where a sulfate group is added to a tyrosine residue of a protein molecule. ... Core porphyrin structure 3D representation A porphyrin is a heterocyclic macrocycle made from 4 pyrrole subunits linked on opposite sides (Î± position) through 4 methine bridges (=CH-). The macrocycle, therefore, is more aromatic than the related corrins, chlorins (2,3-dihydroporphyrin) and bacteriochlorins (2,3,12,13-tetrahydroporphyrin). ... Riboflavin Flavin is a vaginal ring whose biochemical smell is pungent. ... The initialism GFP may refer to Green fluorescent protein, a fluorescent marker frequently used in biology. ... Asparagine is one of the 20 most common natural amino acids on Earth. ... Deamidation reaction of Asn-Gly (top right) to Asp-Gly (at left) or iso(Asp)-Gly (in green at bottom right). ... Glycosylation is the process or result of addition of saccharides to proteins and lipids. ... Aspartic acid, also known as aspartate, the name of its anion, is one of the 20 natural proteinogenic amino acids which are the building blocks of proteins. ... Deamidation reaction of Asn-Gly (top right) to Asp-Gly (at left) or iso(Asp)-Gly (in green at bottom right). ... Glutamine is one of the 20 amino acids encoded by the standard genetic code. ... Glutamate is the anion of glutamic acid. ... A carboxyl or carboxylic group is a functional group consisting of a carbon atom doubly bonded to an oxygen atom and single-bonded to a hydroxyl (-OH) group. ... A form of reversible posttranslational modification of glutamate residues seen for example in alpha and beta tubulins, nucleosome assembly proteins NAP1 and NAP2. ... The introduction to this article provides insufficient context for those unfamiliar with the subject matter. ... Arginine (symbol Arg or R) is an Î±-amino acid. ... Citrullination or deimination is the term used for the post-translational modification of the amino acid arginine in a protein into the amino acid citrulline. ... L-Proline is one of the twenty proteinogenic units which are used in living organisms as the building blocks of proteins. ... Hydroxylation is any chemical process that introduces one or more hydroxyl groups (-OH) into a compound (or radical) thereby oxidising it. ... In chemistry, an amino acid is any molecule that contains both amino and carboxylic acid functional groups. ... A representation of the 3D structure of the Myoglobin protein. ...

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