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Formation of Covalent DNA Adducts by Enzymatically Activated Carcinogens and Drugs In Vitro and Their Determination by 32P-postlabeling
Published on: March 20, 2018
Development of an 125I-postlabeling assay as a simple, rapid, and sensitive index of DNA-protein cross-links
1Nelson Institute of Environmental Medicine, New York University Medical Center, New York 10016.
Abstract:
A rapid, simple, and sensitive 125I-postlabeling technique has been developed to allow detection of DNA-protein cross-links induced by environmental contaminants and carcinogens. This method is based on specific incorporation of 125I into tyrosine residues associated with DNA. Cultured Chinese hamster ovary cells were exposed to various crosslinking agents, e.g., UV light, K2CrO4, or NiCl2. DNA was isolated by proteinase K/phenol/chloroform. The residual peptides cross-linked to DNA were radioiodinated with Na125I and chloramine T. After repeated precipitation with ethanol, the radioactivity was determined. The 125I method was compared with a 3[H]-tyrosine prelabeling method and found to be of similar sensitivity.

