Thermochemistry of Noncovalent Metal-Ligand Bonds of Biological Relevance

Wayne State University, Detroit MI

Investigators

Abstract

Dr. Mary T. Rodgers of Wayne State University is funded for her research on thermochemistry of noncovalent metal-ligand bonds of biological relevance by a grant in the Physical Chemistry program of the Chemistry Division. She will advance her work in the areas of mass spectrometry, chemical reaction dynamics, and gas-phase ion chemistry using the combined techniques of flow tube ion generation coupled with guided ion beam tandem mass spectrometry (GIBMS). These advances include: 1) development of an electrospray ionization (ESI) source coupled with an ion funnel to enable production of nonvolatile and thermally fragile ions in the gas phase and production of multiply charged species; 2) construction of an upgrade of her neutral reactant inlets for both the flow tube and the reaction region; 3) enhancement of computational resources. The proposed research emphasizes three related areas: 1) the determination of absolute bond energies for metal-ligand interactions of biological relevance; 2) development of a thermochemical database of noncovalent metal-ligand interactions of biological relevance; 3) development of threshold collision-induced dissociation and related methods as means to measure accurate thermochemical data on increasingly larger systems. Experimental studies will be supported and enhanced by complementary theoretical work. A prime motivation for this program is to make better correlations between the detailed information provided by gas-phase studies with those of functional biological systems. The pedagogical approach taken, i.e. starting with model systems and gradually increasing the complexity of the systems under investigation was chosen to maximize the probability that thermodynamic information on biological polymers can be obtained with accuracy and precision. Metal ions are involved in all biological processes that nucleic acids (DNA and RNA), the molecules of life participate in. The effects of binding a metal ion to a nucleic acid vary from stabilization of the molecular structure to cell death. This variation in effect results from several possible sites where the metal ion can interact with the nucleic acid: at the phosphate backbone, at the sugar moiety, or at the base. The work is designed to provide fundamental information about the strength of the interactions of metals with the constituents of nucleic acids to elucidate the contributions of particular functional groups to bio-interactions. In this work, a technique that has been specifically designed for the accurate determination of reaction thermochemistry and known as guided ion beam tandem mass spectrometry will be utilized to examine metal ion interactions with chemical species of biological relevance. A coupling of experimental work with theory provides additional insight and also enhances predictive capabilities.