Ethanol radical-induced protein-DNA crosslinking. A radiolysis study.

Aqueous solutions of double-stranded DNA from calf thymus and bovine serum albumin (BSA) were irradiated at pH 7 under N2O and N2 in the presence of 10(-1) mol dm-3 ethanol, which was partly 14C-labelled. Ethanol protects DNA from strand breakage by scavenging OH radicals, but ethanol radicals induce protein-DNA crosslinks. Ethanol radicals react readily with BSA mainly by addition. They react also with double-stranded DNA, but produce crosslinking only very slowly. Based on these results the following mechanism is proposed: ethanol radicals bind to BSA producing protein radicals which become crosslinked to DNA.