In the post-genomic era, a wealth of structural information has been amassed for proteins from NMR and crystallography. In many cases, however, the static protein structures alone are not sufficient to describe their function. Knowledge of the dynamic nature of proteins is essential to understand their wide range of behavior throughout the life cycle from synthesis to degradation. Furthermore, few proteins have the ability to act alone in the crowded cellular environment. Assemblies of multiple proteins governed by complex signaling pathways are often required for the tasks of target recognition, binding, transport and function.

Electrospray mass spectrometry (ESI MS) has emerged over the past several years as a powerful tool to address many of these questions. It provides a means to desorb intact biopolymers (proteins, oligonucleotides, polysaccharides, etc.) from solution to the gas phase. In many cases it is even possible to preserve non-covalent biomolecular complexes and thus obtain information on binding properties in solution (e.g., protein quaternary structure, composition of protein-ligand complexes, etc.). ESI MS is also unique in its ability to detect distinct protein conformers that may co-exist in solution under equilibrium. Concentration requirements are usually very modest, which in many cases allows the biomolecular behavior to be studied at (or even below) the endogenous levels.

Our research is focused on understanding the delicate balance between protein structure and plasticity as related to function. We are particularly interested in understanding the role of protein dynamics (both transient and intrinsic disorder) in such processes as (i) ligand binding, retention and release by transport proteins and (ii) assembly of multi-meric proteins. We are also developing novel mass spectrometry-based strategies to study protein architecture and dynamics. One of them utilizes chemometric tools to detect and characterize multiple protein conformers in solution. Dynamics and structure of these states is probed by a combination of protein chemistry in solution (hydrogen/deuterium exchange to label dynamic segments within the protein) and in the gas phase (protein ion fragmentation to measure the deuterium content across the protein sequence). The latter becomes possible due to a rapid progress in ion fragmentation techniques, which allow primary structure of large biopolymers to be determined in a single experiment.

One of our ultimate goals is to use mass spectrometry to model in vivo processes. Two specific areas of interest include (i) metal transport and delivery by transferrin; and (ii) transport and delivery of vitamin A metabolites by proteins from the Fatty Acid Binding Protein (FABP) family.

You can learn more about our research by browsing through our publications or selecting a link to a specific project: