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J. Am. Chem. SOC.1994,116, 62384244
DNA Adduct Formation by Platinum Anticancer Drugs. Insight into an Unusual GpG Intrastrand Cross-Link in a Hairpin-like DNA Oligonucleotide Using NMR and Distance Geometry Methods Marian Iwamoto, Srinivasan Mukuodan, Jr., and Luigi C. Marzilli’ Contribution from the Department of Chemistty, Emory University, Atlanta, Georgia 30322 Received November 17. 1993.
Abstract: Treatment of a self-complementaryduplex with Pt anticancer drugs leads to formation of an unusual type of hairpin-like oligonucleotide,P ~ ( A ~ ) { S ’ ~ ( A ~ T ~ G ~ G ~ * G S * T & C ~ C & & (A2 ~ = cis-(NH3)20r ethylenediamine (en) and G*’s are platinated at N7). In previous NMR studies, several residues exhibited abnormal upfield- and downfield-shifted 1H and 3lP signals, and one aromatic lH signal, G4*H8, could not be located. In the present study, we found the G4*H8 signal to be broad and shifted -2 ppm upfield into the H1’ spectral region. This shift change is much larger than the theoretical maximum (
