Chemistry Department Seminar: Sashary Ramos, NIH Postdoctoral Fellow
"Spectroscopic Studies of Protein Dynamics and Biological Solvation"
Laboratory of Protein Conformation and Dynamics
Biochemistry and Biophysics Center
National Heart, Lung, and Blood Institute
National Institutes of Health
A complete understanding of biological function requires knowledge of protein conformational dynamics, the structural fluctuations of a protein, and protein hydration. However, the characterization of these properties is challenging due to the inherent complexity of biological systems. For example, proteins are large, heterogenous molecules with motions ranging from the timescale of milliseconds to picoseconds and the heterogeneity of protein systems, stemming from the mixture of hydrophobic and hydrophilic amino acids used as building blocks, further complicates the understanding of protein hydration.
Vibrational spectroscopy has emerged as a powerful tool to directly probe protein conformational dynamics and biological hydration. In the mid-infrared regime, two-dimensional infrared (2D IR) spectroscopy paired with site-specific labeling allows for the investigation into specific protein environments and side-chain dynamics. In this talk, I will present a study exploiting the vibrational probe p-cyano-phenylalanine (CNF) to map very fast (picosecond) conformational changes in a dynamic protein system. I will then transition to the far-infrared regime, also known as the terahertz (THz) regime, and demonstrate how biological water can be mapped as proteins undergo the process of liquid-liquid phase separation (LLPS). LLPS allows for the formation of membrane-less cellular compartments which can be described as nano-reactors in a cell. In addition to the functional roles of LLPS, it is hypothesized that proteins undergo LLPS before entering pathological states, such as the formation of Lewy bodies and amyloids. Although studies have focused on the protein-protein interactions involved in LLPS, it is expected that water also plays a driving force in this process.
Overall, I will present evidence for the importance of fast dynamics and water in protein function and illustrate the rich information provided by vibrational spectroscopy to complement existing biophysical methods.
*This seminar counts towards the chemistry major seminar attendance requirement.