ChBE Seminar Series: Jeffrey Klauda
Friday, October 18, 2013
10:00 a.m.-11:00 a.m.
Room 2108, Chemical and Nuclear Enginering Bldg.
Professor Jeffery Klauda
Molecular Dynamics Studies of Self-Assembly and Biological Membranes
Deprtment of Chemical and Biomolecular Engineering
University of Maryland
Although molecular dynamics (MD) simulations have been used as a tool to probe physical properties of simple gasses and liquids, it has not been until recently ~15 years that this technique has been able to probe timescales of self-assembly and mechanisms of bio-macromolecules. This talk will focus on utilizing all-atom MD to investigate these two areas of research. First, self-assembly simulations of a hydrotrope (tert-butyl alcohol, TBA) in water indicate that these molecules can form quasi-micelles. Hydrotropes are small amphiphilic molecules that alone do not form stable micelles, but can enhance the solubility of hydrophobic substances in water. In collaboration with Dr. Anisimovs lab at UMD, we have found that TBA may act like a surfactant and reduce the water/oil surface tension, which leads to stable mesoscale droplets of oil (~100 nm). Our smaller-scale MD simulations demonstrate the ability of TBA and a water shell to act as a protective coat to oil droplets. A second example of self-assembly is with ester-modified lipids that can laterally self assemble in a membrane and form pores based on our MD simulations. The location of ester groups on the acyl chain is an important factor in pore formation as well as its concentration. Our MD simulations provide important insights into lipid peroxidation and possible biotechnical applications such as drug delivery. Since natural cellular membranes contain a diverse set of lipids, one focus in my lab has been to develop model organism and organelle membranes. Our MD studies on the cytoplasmic membrane of E. coli with its unique lipid containing a cyclopropane moiety on its chain demonstrate the importance of lipid diversity to membrane structure and rigidity. Our E. coli membrane model agrees with known hydrophobic thicknesses of transmembrane proteins and is thinner than existing simple models for the cytoplasmic membrane. These model membranes have and are being used in our lab and by others to study the biological mechanisms of peripheral and transmembrane proteins.