Ion Hydration and New Structural Methods in Mass Spectrometry

University Of California-Berkeley, Berkeley CA

Investigators

Abstract

Professor Evan Williams of the University of California at Berkeley is supported by the Analytical and Surface Chemistry Program to study hydration of amino acids and ions in the gas phase using new methods in mass spectrometry. The research is in two general areas, both involving ion formation by electrospray ionization (ESI) and mass analysis by Fourier-transform ion cyclotron resonance mass spectrometry (FT/ICR MS). The first area is investigating amino acid structures and how both water molecules and metal ions affect these structures. The structures are investigated using infrared (IR) spectroscopy and blackbody infrared radiative dissociation (BIRD). The main goal of these studies is to determine how many water molecules are needed for amino acids to change from nonzwitterion structures (most common in the gas phase) to zwitterion structures (most common in aqueous solution) and how interactions with metal ions influence this structural change. The second area is investigating how ions influence the organization of water itself. These experiments use IR spectroscopy to probe the structures of ions in size-selected nanodrops to determine effects of ion solvation at both short and long distance. The PI has already conducted studies on solvated calcium, sulfate and some simple amino acids. The renewed research project extends such studies to more complex amino acids (arginine, lysine), and more extensively solvated species and will use a broader IR spectral range than was possible previously. Taken together, these experiments should provide a better understanding of how heteroatoms in amino acid side chains and water molecules solvate charge in proteinaceous environments. They also should provide information about how water and the dehydration process in ESI affects ion structure. Mass spectrometry plays an ever increasing role in analytical science, and the proposed research will educate and train scientists in this growing field, which is extensively applied in biology, medicine, and biotechnology research. In addition, this fundamental research on the building blocks of proteins will enable researchers to sequence proteins more rapidly and accurately.