Radioactive Methylation
Radioactive Methylation - Related Videos
03:18
Radioactivity and Nuclear Equations
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2020
Nuclear chemistry is the study of reactions that involve changes in nuclear structure. The nucleus of an atom is composed of protons and, except for hydrogen, neutrons. The number of protons in the nucleus is called the atomic number (Z) of the element, and the sum of the number of protons and the number of neutrons is the mass number (A). Atoms with the same atomic number but different mass numbers are isotopes of the same element. A nuclide of an element has a specific number of protons and...
02:48
Radioactive Decay and Radiometric Dating
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2020
Radioactivity is a spontaneous disintegration of an unstable nuclide and is a random process, as all the nuclei in the sample do not decay simultaneously. The number of disintegrations per unit time is called the activity (A), which is directly proportional to the number of nuclei in the sample. The decay constant (λ) is an average probability of decay per nucleus in unit time. The SI unit for activity is the becquerel, which is one disintegration per second. Another unit of activity is the...
08:47
DNA Methylation Analysis
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2023
Methylation at CpG dinucleotides is a chemical modification of DNA hypothesized to play important roles in regulating gene expression. In particular, the methylation of clusters of methylation sites, called “CpG islands”, near promoters and other gene regulatory elements may contribute to the stable silencing of genes, for example, during epigenetic processes such as genomic imprinting and X-chromosome inactivation. At the same time, aberrant CpG methylation has been shown to be associated with...
21:24
Methylated DNA Immunoprecipitation
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Cited by 43 •
2009
This video demonstrates the protocol for methylated DNA immunoprecipitation (MeDIP). MeDIP is a two day procedure that selectively extracts methylated DNA fragments from a genomic DNA sample using antibodies with specificity for 5 -methylcytosine (anti-5 mC).
03:23
Types of Radioactivity
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2020
The most common types of radioactivity are α decay, β decay, γ decay, neutron emission, and electron capture. Alpha (α) decay is the emission of an α particle from the nucleus. For example, polonium-210 undergoes α decay: Alpha decay occurs primarily in heavy nuclei (A > 200, Z > 83). Loss of an α particle gives a daughter nuclide with a mass number four units smaller and an atomic number two units smaller than those of the parent nuclide. Beta (β) decay is the emission of an electron or...
FAQs
A methyltransferase uses a donor such as S-adenosyl-L-methionine to transfer a methyl group onto a biological substrate. When that methyl group is radiolabeled, the resulting modification carries a detectable radioactive signal. The signal links methyltransferase activity to product formation, enabling researchers to follow methyl-transfer reactions rather than merely infer that a reaction occurred.
The assay can examine methylation of DNA, RNA, proteins, and small molecules. This range allows investigators to study different classes of methyltransferases and determine which molecular targets are modified. Comparing substrates helps reveal whether an enzyme acts selectively on one type of molecule or participates in a broader methylation pathway.
Researchers compare the radioactive labeling associated with products formed under different reaction conditions. Greater or lower product-associated radioactivity can indicate corresponding changes in methyl-transfer activity, allowing reaction rates to be compared. This approach is useful for characterizing enzyme behavior and assessing how experimental conditions influence the extent of methylation.
A typical assay combines a methyltransferase, a suitable biological substrate, and a methyl donor such as S-adenosyl-L-methionine containing a radiolabeled methyl group. During incubation, the enzyme transfers the label to the substrate. The modified products are then tracked through their radioactivity, providing a measure of methyl-transfer activity and product formation.
Researchers can use the technique when they need to determine whether a DNA, RNA, protein, or small molecule receives a methyl group during an enzymatic reaction. Detecting radioactivity in the modified product connects the enzyme with that target. This supports studies of methyltransferase specificity and helps characterize previously examined methylation pathways.
In epigenetics, the approach helps investigate methylation reactions involving DNA and their relationship to gene regulation. In RNA biology, it supports analysis of methylation associated with RNA processing. The same strategy also examines protein modification and broader cellular methylation pathways, providing experimental context for understanding cellular function and disease-related mechanisms.