| Autor: |
Meikle TG; School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia., Keizer DW; Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia., Babon JJ; The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia.; Department of Medical Biology, The University of Melbourne, Melbourne, VIC 3010, Australia., Drummond CJ; School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia., Separovic F; Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia.; School of Chemistry, The University of Melbourne, Melbourne, VIC 3010, Australia., Conn CE; School of Science, College of Science, Engineering and Health, RMIT University, Melbourne, VIC 3000, Australia., Yao S; Bio21 Molecular Science and Biotechnology Institute, The University of Melbourne, Melbourne, VIC 3010, Australia. |
| Abstrakt: |
Proton transportation in proximity to the lipid bilayer membrane surface, where chemical exchange represents a primary pathway, is of significant interest in many applications including cellular energy turnover underlying ATP synthesis, transmembrane mobility, and transport. Lipidic inverse bicontinuous cubic phases (LCPs) are unique membrane structures formed via the spontaneous self-assembly of certain lipids in an aqueous environment. They feature two networks of water channels, separated by a single lipid bilayer which approximates the geometry of a triply periodic minimal surface. When composed of monoolein, the LCP bilayer features two glycerol hydroxyl groups at the lipid-water interface which undergo exchange with water. Depending on the conditions of the aqueous solution used in the formation of LCPs, both resonances of the glycerol hydroxyl groups may be observed by solution 1 H NMR. In this study, PFG-NMR and 1D EXSY were employed to gain insight into chemical exchange between the monoolein hydroxyl groups and water in LCPs. Results including the relative population of hydroxyl protons in exchange with water for a number of LCPs at different hydration levels and the exchange rate constants at 35 wt % hydration are reported. Several technical aspects of PFG-NMR and EXSY-NMR for the characterization of chemical exchange in LCPs are discussed, including an alternative way to analyze PFG-NMR data of exchange systems which overcomes the inherent low sensitivity at high diffusion encoding. |
