Event
Special Bioengineering Seminar: Silvina Matysiak
Thursday, March 11, 2010
11:00 a.m.
Room 1105, Jeong. H. Kim Engineering Building
Professor Sameer Shah
sameer@umd.edu
Understanding Protein Stability and the Folding Mechanism
Presented by Silvina Matysiak
Department of Chemistry and Biochemistry
Institute of Computational Sciences and Engineering
University of Texas at Austin
Proteins are the nanomachines of biology. They possess a well-defined functional native conformation that is stable within a limited range of temperatures, pressures, and solvent conditions.Several diseases including Alzheimer's and Parkinson's are associated with the formation of amyloid fibrils by self-assembly of misfolded proteins. Proteins are not static structures, in order to function they have to explore their energy landscape so a detailed characterization of the folding landscape is critical and would aid in the design of new proteins for a variety of applications, including pharmaceuticals, enzyme catalysis and biomaterials.
The detailed characterization of the overall free energy landscape associated with the folding process of a protein is the ultimate goal in protein folding studies. Modern experimental techniques provide accurate thermodynamic and kinetic measurements on restricted regions of a protein landscape.
Although simplified protein models can access larger regions of the landscape, they are oftentimes built on assumptions and approximations that affect the accuracy of the results. In the first part of my talk I will present new methodologies that allows to combine the complementary strengths of theory and experiment for a more complete characterization of a protein folding landscape. Recent results on the interplay between folding/misfolding and aggregation in protein S6 will be discussed.
In the second part of my talk I will discuss the microscopic mechanism of cold and heat denaturation using a 3D lattice model of a protein in which water is represented explicitly. We find that changes of hydrophobic hydration with low temperatures induces cold denaturation and is enthalpic driven whereas heat denaturation is entropic driven. The cold denatured states are compact and solvent-penetrated rather than completely unfolded, indicating a different thermodynamic state as the heat denatured one.
