Identification of Nuclearity of Chromium Binary Adducts with DNA by Negative Ion Mass Spectrometry: Short Communication.

Chromium(VI) is a carcinogen and mutagen, and its mechanism of action is proposed to involve binding of its reduction product, chromium(III), to DNA. Recently, this laboratory has shown that small oligonucleotide duplexes of DNA can be used to generate binary adducts of Cr(III). The structure of the Cr(III) binding site on the duplex DNA can be established using a combination of paramagnetic NMR, EPR, and FTIR spectroscopies. These studies have shown that aquated mononuclear Cr(III) or aquated hydroxo-bridged binuclear Cr(III) moieties bind to N-7 of guanine residues of the DNA depending on the DNA sequence. In the past determining which of these binary adducts formed required time-consuming variable temperature magnetic susceptibility and related experiments. Negative ion mass spectrometry (MS) can be utilized to efficiently identify whether mononuclear or binuclear binary Cr(III) adducts are formed.