Profs. Igor Kaltashov and Stephen Eyles at the University of Massachusetts - Amherst are supported by the Analytical and Surface Chemistry Program to investigate the structure, assembly, and dynamic properties of biomolecules and synthetic polymers using electrospray ionization (ESI) mass spectrometry. Their studies probe the charge states exhibited in ESI mass spectra under carefully controlled experimental conditions to evaluate solution phase conformations. The goal is to develop a powerful tool for solving a diverse set of problems in biophysics and nanotechnology. Of particular interest are the molecular mechanisms of blood clotting modulated by the oligosaccharide heparin, the conformational transitions of intrinsically disordered proteins that can lead to disease states, and understanding how proteins conjugated to synthetic polymers - a rapidly expanding field in therapeutic drug development - interact with their biological targets.
Broader impacts of the research stem from the development of a comprehensive experimental strategy for probing macromolecular conformation and dynamics in complex multi-component systems - capability urgently needed in diverse fields ranging from biophysics to nanomedicine. In pursuing these aims, a diverse group of undergraduate and graduate students engages in interdisciplinary scientific discovery involving high end mass spectrometry instrumentation, providing a valuable training arena to young scientists.
We developed several analytical procedures that can be used to probe structure and behavior of complex biomolecules that are frequently encountered in biotechnology and biopharmaceuticals, such as proteins, protein-polymer conjugates, etc. These molecules frequently exhibit structural heterogeneity, which makes their characterization with classical analytical techniques extremely difficult or indeed impossible. Inadequate structural characterization of biotechnological and biopharmaceutical products may have devastating consequences, since minute structural changes frequently result in loss of the drug’s efficacy and compromise its safety by triggering immune response. The new analytical technique is based on mass spectrometry, and also uses chemical reactions in the gas phase to manipulate large macromolecular ions in order to extract important structural information. It can also be used to monitor protein aggregation, a process that negatively affects the quality of many biopharmaceutical products, and is frequently encountered in other areas of medicine (for example, it is associated with several diseases such as Alzheimer’s and Parkinson’s). Unfortunately, the existing techniques that are commonly used to follow and characterize protein aggregation have significant limitations. For example, methods such as analytical ultracentrifugation and size exclusion chromatography can provide only low-resolution data. The poor resolution makes it difficult to distinguish between aggregates (protein clamps) of different sizes. Furthermore, size exclusion chromatography can take tens of minutes, a delay that means researchers can miss important events as the proteins aggregate. The new mass spectrometry method has a clear advantage, because it easily separates each mass of the different-sized aggregates. This new method will become a welcome addition to the analytical arsenal in the biopharmaceutical industry.
