Related Experiment Video
Updated: Feb 19, 2026

DNA Methylation: Bisulphite Modification and Analysis
Published on: October 21, 2011
How does methylation suppress the electron-induced decomposition of 1-methyl-nitroimidazoles?
F Kossoski1, M T do N Varella2
1Instituto de Física "Gleb Wataghin", Universidade Estadual de Campinas, 13083-859 Campinas, São Paulo, Brazil.
Abstract:
The efficient decomposition of nitroimidazoles (NIs) by low energy electrons is believed to underlie their radiosensitizing properties. Recent dissociative electron attachment (DEA) measurements showed that methylation at the N1 site unexpectedly suppresses the electron-induced reactions in 4(5)-NI. We report theoretical results that provide a clear interpretation of that astounding finding. Around 1.5 eV, DEA reactions into several fragments are initiated by a π* resonance, not considered in previous studies. The autoionization lifetime of this anion state, which limits the predissociation dynamics, is considerably shorter in the methylated species, thereby suppressing the DEA signals. On the other hand, the lifetime of the π* resonance located around 3 eV is less affected by methylation, which explains why DEA is still observed at these energies. Our results demonstrate how even a simple methylation can significantly modify the probabilities for DEA reactions, which may be significant for NI-based cancer therapy.
More Related Videos
06:07Continuous Fluorescence-Based Endonuclease-Coupled DNA Methylation Assay to Screen for DNA Methyltransferase Inhibitors
Published on: August 5, 2022
07:38A General Method for Detecting Nitrosamide Formation in the In Vitro Metabolism of Nitrosamines by Cytochrome P450s
Published on: September 25, 2017
Related Concept Videos
Carboxylic Acids to Methylesters: Alkylation using Diazomethane
Phase II Reactions: Methylation Reactions
The mechanism of methylation unfolds in two stages. The first stage sees a methyltransferase enzyme facilitating the transfer of a methyl group from S-adenosylmethionine (SAM) to the substrate, forming S-adenosylhomocysteine (SAH). The second stage involves further metabolism of SAH into homocysteine, which can be recycled...
meta-Directing Deactivators: –NO2, –CN, –CHO, –⁠CO2R, –COR, –CO2H
2° Amines to N-Nitrosamines: Reaction with NaNO2
Aldehydes and Ketones with Amines: Imine Formation Mechanism
Imines are formed under mildly acidic conditions. A pH of 4.5 is ideal for the reaction.
If the pH is low or the solution is too acidic, the reaction slows down in the...
Spontaneous and Induced Mutations