KSEF RDE: Probing Metal Binding to NDA and RNA Nucleobases with High-Resolustion Photoelectron Spectroscopy

The presence of metal ions in the cell nucleus affects the formation, replication, and cleavage of DNA and RNA. Depending on the type and concentration, metal ions may stabilize the nucleic acid chain through charge neutralization or disrupt hydrogen bonds by attaching to nucleobases. The nucleobases in DNA and RNA include cytosine, guanine, adenine, thymine, and uracil; each of these bases offers several different coordination sites for metal ions. The nature and site of metal binding influence base pairing and the course of genetic information transfer. We propose a novel approach to probe optimal metal locations around these nucleobases in an isolated environment, where interferences from other chemical species are removed. We will use laser-assisted reactions to prepare metal-nucleobase complexes in gaseous supersonic jets, mass spectrometry to measure the abundance and distribution of reaction products, and highresolution photoelectron spectroscopy to search for electronic-vibrational spectra. This photoelectron technique, called pulsed field ionization-zero electron kinetic energy (ZEKE) spectroscopy, provides spectral resolution superior to conventional photoelectron methods. The success of the proposed work will yield an unprecedented knowledge about fundamental interactions in selected metal-nucleobase systems, which includes accurate ionization and vibrational energies, metal binding sites, and molecular structures. Moreover, this research will open a new application of high-resolution photoelectron spectroscopy to bioinorganic chemical systems, enhance Kentucky's emerging international reputation in this field, and increase our capability to compete for more national research grants.