Repair of O6-ethylguanine in DNA by a chromatin fraction from rat liver: transfer of the ethyl group to an acceptor protein.
- 1 November 1981
- journal article
- research article
- Published by Proceedings of the National Academy of Sciences in Proceedings of the National Academy of Sciences
- Vol. 78 (11) , 6766-6770
- https://doi.org/10.1073/pnas.78.11.6766
Abstract
Incubation of O6-[3H]ethylguanine-containing [calf thymus] DNA with a rat liver chromatin fraction resulted in a decrease in the O6-ethylguanine content of the DNA. Analysis of the products of this reaction showed that the ethyl group had been transferred from the O6-ethylguanine to a protein acceptor. When the incubation mixture was separated on a cesium chloride gradient, the radioactivity removed from O6-ethylguanine appeared in a low-density band. This material was isolated and subjected to trypsin digestion and high-pressure liquid chromatography analysis; it was sensitive to trypsin and the digest contained new high-pressure liquid chromatography peaks characteristic of oligopeptides. Radioactive peaks from trypsin digestion were digested further to the amino acid level and were shown to contain S-[3H]ethylcysteine. Thus, the repair activity in rat liver chromatin removes the ethyl group from 06-ethylguanine and transfers it to a cysteine moiety contained in an acceptor protein. [O6-ethylguanine and other O-substituted bases have been implicated as initial mutagenic lesions produced by carcinogens.].This publication has 20 references indexed in Scilit:
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