DNA Cleavage by the Photolysis of Cyclopentadienyl Metal Complexes: Mechanistic Studies and Sequence Selectivity of Strand Scission by CpW(CO)3CH3.

The photolysis of CpW(CO)3Me has been shown to produce methyl radicals and to cleave DNA in a single-stranded manner, and preliminary evidence implicated a carbon-centered radical in this process. In this work, the mechanism of strand scission in this reaction was determined to occur by hydrogen atom abstraction from the 4′- and 5′-positions of the deoxyribose moiety of the backbone of DNA. Additionally, in a side reaction that does not lead to frank strand scission, all four bases of DNA are methylated under these conditions; however, none of these base or backbone modifications lead to the formation of abasic sites. [ABSTRACT FROM AUTHOR]