%0 Journal Article %A Johnstone, Timothy C. %A Lippard, Stephen J. %D 2015 %T The Chiral Potential of Phenanthriplatin and Its Influence on Guanine Binding %U https://acs.figshare.com/articles/journal_contribution/The_Chiral_Potential_of_Phenanthriplatin_and_Its_Influence_on_Guanine_Binding/2028192 %R 10.1021/ja4125115.s001 %2 https://acs.figshare.com/ndownloader/files/3599499 %K carbonyl oxygen %K intramolecular interaction %K phenanthridine ligand racemizes %K platinated guanine base %K molecule models %K covalent bond %K NMR spectra %K anticancer activity %K diastereomeric phenanthriplatin analogs %K diastereomeric form %K NMR spectroscopic %K bifunctional compounds %K DNA %K Guanine BindingThe monofunctional platinum %X The monofunctional platinum complex cis-[Pt­(NH3)2Cl­(Am)]+, also known as phenanthriplatin, where Am is the N-heterocyclic base phenanthridine, has promising anticancer activity. Unlike bifunctional compounds such as cisplatin, phenanthriplatin can form only one covalent bond to DNA. Another distinguishing feature is that phenanthriplatin is chiral. Rotation about the Pt–N bond of the phenanthridine ligand racemizes the complex, and the question arises as to whether this process is sufficiently slow under physiological conditions to impact its DNA-binding properties. Here we present the results of NMR spectroscopic, X-ray crystallographic, molecular dynamics, and density functional theoretical investigations of diastereomeric phenanthriplatin analogs in order to probe the internal dynamics of phenanthriplatin. These results reveal that phenanthriplatin rapidly racemizes under physiological conditions. The information also facilitated the interpretation of the NMR spectra of small molecule models of phenanthriplatin-platinated DNA. These studies indicate, inter alia, that one diastereomeric form of the complexes cis-[Pt­(NH3)2(Am)­(R-Gua)]2+, where R-Gua is 9-methyl- or 9-ethylguanine, is preferred over the other, the origin of which stems from an intramolecular interaction between the carbonyl oxygen of the platinated guanine base and a cis-coordinated ammine. The relevance of this finding to the DNA-damaging properties of phenanthriplatin and its biological activity is discussed. %I ACS Publications