Reductive Methylation
Reductive Methylation - Related Videos
13:59
Methods to Identify the NMR Resonances of the 13C-Dimethyl N-terminal Amine on Reductively Methylated Proteins
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Cited by 4 •
2013
Two methods for assigning the α- and ε-dimethylamine nuclear magnetic resonance signals of a reductively 13C-methylated N-terminal lysine are described. One method utilizes the pH-induced selectivity of the reductive methylation reaction, and the other uses aminopeptidase to selectively remove the N-terminal lysine.
08:00
Sample Preparation and Relative Quantitation using Reductive Methylation of Amines for Peptidomics Studies
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Cited by 1 •
2021
This article describes a sample preparation method based on heat-inactivation to preserve endogenous peptides avoiding degradation post-mortem, followed by relative quantitation using isotopic labeling plus LC-MS.
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).
03:11
Oxidation-Reduction Reactions
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2020
Oxidation–Reduction Reactions Earth’s atmosphere contains about 20% molecular oxygen, O2, a chemically reactive gas that plays an essential role in the metabolism of aerobic organisms and in many environmental processes that shape the world. The term oxidation was originally used to describe chemical reactions involving O2, but its meaning has evolved to refer to a broad and important reaction class known as oxidation–reduction (redox) reactions. Some redox reactions involve the transfer of...
FAQs
Reaction access determines which sites become labeled. Primary amines must be accessible, so protein N termini and lysine side chains are especially relevant targets. This site dependence helps researchers interpret labeling patterns: an unmodified or less represented group may reflect limited accessibility rather than absence of the amino group. That distinction matters when relating modification patterns to protein structure or interactions.
Formaldehyde first reacts with an accessible primary amine to form an imine intermediate. Sodium borohydride then reduces that intermediate, converting it into a stable methylated amine. Repeating the reaction sequence can add a second methyl group and produce dimethylation. Separating these roles clarifies why both reagents are required for the overall labeling chemistry.
Repeated cycles can convert a primary amine through methylation and onward to dimethylation, changing the chemical state of the labeled group. Because the modification affects properties such as charge, solubility, and molecular interactions, the extent of labeling can influence how a protein behaves experimentally. Researchers therefore need to relate the methylation state to the biological or structural question being studied.
A basic workflow exposes a biomolecule containing accessible primary amines to formaldehyde, allows imine formation, and then adds sodium borohydride to reduce the intermediate. Researchers may repeat the reaction to promote dimethylation, then examine the modified material with an appropriate analytical method. The workflow connects chemical labeling to later measurements of identity, quantity, conformation, or interactions.
Mass spectrometry can detect the chemical changes introduced at protein N termini or lysine side chains. Those mass changes provide labeling information that helps researchers identify proteins and quantify them. The method is therefore useful when a controlled modification improves the distinction or measurement of protein signals, while the observed pattern can also indicate which amines were accessible during treatment.
The modification can support nuclear magnetic resonance and X-ray crystallography by changing selected protein features that are relevant to experimental analysis. It may also alter charge, solubility, or molecular interactions, which can affect how a protein behaves in a structural study. Researchers use these effects to probe conformation and improve interpretation or quality of structural measurements.