Materials Science and Engineering Seminar Series: Antonio Faraone
Friday, April 1, 2011
1:00 p.m.-2:00 p.m.
Room 2108, Chemical and Nuclear Engineering Bldg.
Collective Nanoscale Dynamics in Systems of Biological Relevance: Protein Domain Motions and Membranes Elasticity
The activity of biological systems is related to configurational changes and motions corresponding to length and timescale ranging from sub-Angstrom and picoseconds to nanometers and several tens of nanoseconds and beyond. Using Neutron Spin Echo Spectroscopy (NSE), the nanoscale dynamics of two systems of biological relevance were investigated. The aim of the studies was a deeper understanding of the relationship in the form-function-dynamics triad. In particular, lysozyme partially unfolded using the photoresponsive surfactant azoTAB was shown to have significantly higher activity than the native state. The NSE investigation demonstrated enhanced nanoscale dynamics of the protein in its partially unfolded state. This result gives insight into a unique light-based method of controlling protein structure, dynamics, and activity. Similarly, the thermal fluctuation and elasticity of dioleoyl-phosphocholine large unilamellar vesicles interacting with the pore-forming peptide melittin, were investigated. The bending rigidity of the membrane at different peptide to lipid molar ratio shows a complex behavior. The obtained results can be understood in terms of thinning/thickening of the membrane, disordering of the hydrocarbon chain in the bilayer, and interaction between adsorbed peptides. Both studies highlight the relevance of the nano-meter nano-second scale for the understanding of biological systems.