Related Experiment Video
Updated: Oct 3, 2026

A General Method for Detecting Nitrosamide Formation in the In Vitro Metabolism of Nitrosamines by Cytochrome P450s
Published on: September 25, 2017
Effects of ethylating agents on DNA synthesis in vitro: implications for the mechanism of carcinogenesis
Abstract:
A highly carcinogenic ethylating agent, ethylnitrosourea (ENU), and a weakly carcinogenic one, diethylsulfate (DES) react with DNA to roughly the same extent but DES produces about 6 times as many unstable ethylated bases, which are gradually lost spontaneously under physiological conditions. The different rates of loss for the different DNA bases have been studied using polydeoxyribonucleotides. Spontaneous strand breakage following base loss is slow, lagging more than a week behind base loss at 37 degrees C; ultimately, DES results in much more spontaneous strand breakage than ENU. In DNA synthesis in vitro, using avian myeloblastosis virus (AMV) polymerase, no nucleotides are incorporated opposite missing bases in the template; when the template contains ethylated bases that are impaired in their ability to form specific hydrogen bonds, purine-pyrimidine mispairing can occur and mismatched nucleotides are incorporated into the daughter strand. ENU ethylates somewhat more sites leading to mispairing potential than DES. ENU also produces approximately 7.5 times more ethyl phosphotriesters than DES.
More Related Videos
09:33Formation of Covalent DNA Adducts by Enzymatically Activated Carcinogens and Drugs In Vitro and Their Determination by 32P-postlabeling
Published on: March 20, 2018
12:15Quantification of three DNA Lesions by Mass Spectrometry and Assessment of Their Levels in Tissues of Mice Exposed to Ambient Fine Particulate Matter
Published on: May 29, 2019
Related Concept Videos
DNA Damage can Stall the Cell Cycle
Carboxylic Acids to Methylesters: Alkylation using Diazomethane
DNA Damage Can Stall the Cell Cycle
Mutagenicity and Carcinogenicity
Spontaneous and Induced Mutations
Inhibitors of Bacterial DNA Synthesis