Elucidating Factors Affecting the Preservation of Biomolecule Solution Structure for Spray-based Ionization Processes

With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, and the Established Program to Stimulate Competitive Research (EPSCoR), Stephen Valentine, Peng Li and Matthew Johnson and their groups at West Virginia University are developing new methods to study the structures of biological macromolecules such as proteins. These molecules must foldinto very specific three-dimensional (3D) structures in order to perform their required biological functions. Drs. Valentine, Li, and Johnson are developing new tools for generating micrometer-sized droplets of varying charge that allow the study of challenging biomolecules in solution using mass spectrometry (MS) techniques. The proposed studies provide fundamental knowledge required to conduct the most efficient MS measurements for biomolecule structure determination. In the future, this knowledge can be used to study disease processes as well as to develop biomolecular drugs. The work also provides valuable technology exposure to diverse graduate and undergraduate students in the areas of MS measurement and instrumentation development. The Valentine/Li/Johnson team at West Virginia University is developing a new approach to examine biomolecular structure using native MS. Recent experiments have shown that the technology of vibrating sharp-edge spray ionization (VSSI), when operated in a voltage-free mode for native MS experiments, can better preserve the structures of challenging proteins such as those possessing regions of disorder. For ion production, VSSI provides the ability to decouple the processes of droplet charging and droplet production in contrast to the Coloumbically-driven process encountered in electrospray ionization (ESI). Thus, with VSSI, it appears to now be possible to map protein structure transformations associated with specific droplet conditions. In this study the relationships between such transformations and droplet characteristics such as overall charge, diameter, and temperature equilibration with the heated capillary will be examined. The scientific knowledge gained from these studies will be shared publicly and can then be used to guide scientists with regard to best nanoelectropsray ionization (nESI) practices for studying the structures of challenging biomolecular species. In this way, the work has the potential for broad scientific impact across diverse fields from protein biophysics, to protein biocatalysis, to proteomics to human biology and biomedical science. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.