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Probing Metal Binding to DNA and RNA Nucleobases with High-Resolution Photoelectron Spectroscopy
University of Kentucky 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 present 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 high-resolution photoelectron spectroscopy to search for electronic-vibrational spectra. This photoelectron technique, called pulsed field ionization-zero electron kinetic energy spectroscopy, provides spectral resolution of tens of times better than that of conventional photoelectron methods. The outputs of this research will include accurate ionization and vibrational energies, metal binding sites, and molecular structures. The success of this work will open new applications 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.
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