Book of Abstracts: Albany 2003
June 17-21 2003
Complexes of Cisplatin with d(CCTGGTCC)·d(GGACCAGG) and d(CCTCTGGTCTCC)·d(GGAGACCAGAGG) by VCD and IR
The structures of the complexes of cisplatin with both title oligomers in aqueous solution have been determined authoritatively by NMR (1,2). Compared to NMR, vibrational circular dichroism (VCD) is a relatively new spectroscopic technique, which has not yet been applied sufficiently frequently to authenticate changes of DNA structure in response to various agents in order to become universally accepted as a viable spectroscopic tool for this purpose. In the meantime, we used VCD very successfully as a complementary technique, which often is superior to infrared absorption for extracting structural information for DNA complexes with Mn2+, Cu2+, and Cr3+ ions (3,4). The goal of this investigation, therefore, was to test the capabilities of VCD on cisplatin complexes initially with selected synthetic oligonucleotides for which structural information was available for comparison.
The VCD spectra of both title oligomers when complexed with cis-platin in aqueous solution showed distinctive and characteristic changes in exquisite detail compared to infrared absorption. We were able to explain these changes in terms of the structural information deduced by NMR. VCD features were particularly informative for the platination site where the normal stacking of the base pairs is severely disrupted by the formation of the complex between the platinum atom and adjacent guanines in the oligomers.
1Institute of Organic Chemistry