Grant: Discovery Grants Program - Individual

) ) Lipid molecules dispersed in water assemble into thin layers with polar headgroups on the outside and flexible hydrocarbon chains inside. These bilayers are important as soft materials and as the structural basis for cell membranes. By applying wideline NMR to model systems with deuterated components, we learn how composition and component structure affect the organization, mechanical properties, and motion of components in such materials and address questions of both material and biological significance. ) We are one of only a few groups worldwide able to apply NMR to model membranes under pressure. We use this to relate molecular characteristics to the way in which bilayers are perturbed by pressure and to observe bilayer states not otherwise accessible. How bilayers respond to pressure can give insight into their properties at normal pressure, guide theoretical studies, and help to show how marine organisms survive pressure changes. ) We also look at how bilayer properties are modified by embedded proteins and conversely, using NMR observations of deuterium-labelled model polypeptides, how motions of embedded transmembrane proteins are affected by bilayer properties. This contributes to our understanding of bilayer mechanical properties and of transmembrane processes essential to biological cell function. ) Breathing is made possible by a lipid layer that reduces surface tension at the air-water interface in lungs. We collaborate with life science colleagues to study how embedded proteins enable transfer and reorganization of material from bilayer reservoirs to this surfactant layer. This contributes to development of artificial surfactants for treatment of lung problems and to development of strategies for control of large-scale organization in self-assembled lipid-like materials. ) ) Another line of study in our group is the issue of how structural characteristics of specific bilayer components, including different lipid classes and proteins, affect their mixing properties in bilayers. This is timely given increasing recognition of a role for membrane heterogeneity in the control of membrane protein activity.