Our lab specializes in dynamic measurements of structure and organization of soft condensed matter systems. In particular, we are interested in the relationship between solvent structure, lipid dynamics, and protein structure and self-assembly. We use a combination of ultrafast spectroscopy and fluorescence microscopy to conduct our experiments. Time-resolved fluorescence anisotropy microscopy is used to characterize lipid phase transitions and self-assembly of membrane molecules at the air-water interface. Ultrafast fluorescence up-conversion spectroscopy is used to investigate hydration dynamics and molecular interactions at the surface of proteins. Using these techniques we can investigate interactions between proteins and their coordinating solvent molecules, and develop techniques to modify and manipulate these interactions thereby influencing protein structure and function.
We have developed and constructed a time-resolved fluorescence microscope capable of measuring the 3-dimensional dynamic freedom of lipids and proteins in monolayers at the air-water interface, with unprecedented spatial and temporal resolution. Structural biologists havelong focused on the relationship between protein structure and function in investigating biological processes. Less recognized is the essential role the solvent plays in dictating structural transitions and self- assembly. Lipid phase stability and clustering are essential to the recognition, insertion, and self-assembly of proteins within the lipid membrane. Using our techniques we can resolve these highly dynamic processes to unambiguously identify orientation, interactions, and dynamic freedom within our membrane model with the highest available temporal resolution, and without the restrictions imposed by a supporting substrate.
Water at the surface of a protein defines a molecular layer that exhibits unique characteristics. The structure and dynamics of such layers, are important for the stability of proteins as well as for the mechanisms of protein-protein and protein-ligand association. Time-resolved fluorescence studies provide very detailed experimental information about the dynamics of solvation. In particular, the fluorescence frequency up-conversion method monitors solvation dynamics by following the evolution of the emission spectrum of a chromophore in solution. The time resolution afforded by this technique is on the timescale in which solvent relaxation occurs. Using this technique we can accurately map out changes in the hydration layer dynamics and protein stability induced either through protein modification or through interaction with neighboring solutes.
We have research opportunities available for undergraduate students interested in research at the interface of physics and biology. I encourage all interested students to stop by my office, Exley 233, to discuss research opportunities in the physics department at Wesleyan.
