Comparison of cis and trans-platinum mononucleobase compounds with DNA and protein models

Reactions of 5'-guanosine monophosphate (5'-GMP) and N-acetylmethionine (N-ac-L-Met) with the mononucleobase compounds, cis-[PtCl(L)(n)(9-EtGH)](+) (L = NH3, 4-pic, n = 2; L = en, n = 1) in a 1: 1 molar ratio have been studied in aqueous solutions at pH 7.3 using H-1 and Pt-195 NMR spectroscopy. There is a high kinetic preference for sulfur over nitrogen binding. These results are compared with the trans isomers. Based on low cytotoxicity and a high sulfur/nitrogen preference the cis isomers may also present suitable features for antiviral activity through interaction with specific proteins.