Probing Effects on DNA Structure upon Interaction with Various Agents by Vibrational Circular Dichroism Spectroscopy
The possibility that absorptions arising from molecular vibrations should inherently exhibit circular dichroic character was first considered theoretically in 1968 for a model helical polymer.1 Experimental measurements, however, were not a trivial matter. The first experimental vibrational circular dichroism (VCD) spectra were reported in 1972 for a complex of Pr3+ with L-tartrate, and in 1973 for crystalline a-NiSO4.6H2O.2,3 The first reports of VCD applied to biopolymers appeared in 1981 for polypeptides, and in 1987 for DNA.4,5 Thereafter, the groups of T.A. Keiderling and M. Diem explored in a flurry of activity the origin of VCD signals in DNA, as well as a number of fundamental aspects of DNA structure.6,7.
In our laboratory, we began to investigate DNA structure and dynamics by VCD spectroscopy in 1993. In this report, we summarize the highlights of our journey, using our observations as examples of characteristic VCD features that result from differing nucleobase sequences, interaction with divalent and trivalent metal ions, selected drug molecules, RNA-DNA hybrids, and parallel stranded DNA. The underlying objectives of this report are to emphasize particular strengths as well as weaknesses of this relatively new spectroscopic technique, and whether and in what respect it might become an effective tool for elucidating DNA structures and dynamics.
1. C.W. Deutsche and A. Moscowitz, J. Chem. Phys. 49, 3257-3272 (1968); ibid. 53, 2630-2644 (1970).
H. Wieser, V. Andrushchenko, M. Krasteva, V.Maharaj , A. Pandyra, D. Tsankov and J.H. van de Sande1
Department of Chemistry, Faculty of Science,