Solubilisation of lipid membranes by detergents: probing the three-state model at the single vesicle level

Quinn, S. D. , Deas, L. A., Dalgarno, P. A., Hedley, G. J. , Samuel, I. D.W. and Penedo, C. (2013) Solubilisation of lipid membranes by detergents: probing the three-state model at the single vesicle level. Biophysical Journal, 104(2), 174a. (doi: 10.1016/j.bpj.2012.11.979)

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The solubilisation of lipid membranes by detergents is a common technique in the purification and isolation of proteins and in the study of membrane proteins. Biophysical studies of these solubilisation processes using ensemble-averaging techniques have provided an integrated picture of the solubilisation mechanism that involves three states: the detergent is taken up in stage I without solubilisation (vesicle regime); stage II refers to the coexistence of detergent-saturated membranes and mixed detergent-lipid micelles and finally stage III corresponds to complete membrane solubilisation leading to the formation of mixed micelles (micellar regime). Although the three-state hypothesis is a didactic and simple thermodynamic model, it is known that detergent lipid-interactions induce a much more complex and diverse dynamic transition between both regimes. These dynamic changes include transmembrane lipid motion (flip-flop), swelling and breakdown of the membrane permeability barrier and fusion between vesicles. To date, whether these processes are independent of each other and take place sequentially, or if they are somehow interconnected is an open question. Here, we have used single-molecule FRET to monitor the solubilisation dynamics of single POPC/POPS vesicles induced by the non-ionic detergent Triton-X 100. Using this approach we have been able to unambiguously separate within a single FRET trajectory the swelling, permeabilization and lysis steps of the solubilisation process and their kinetic details above and below the critical micellar concentration. The present strategy should help in the design of more efficient applications of vesicle solubilisation.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Quinn, Dr Steven and Hedley, Dr Gordon
Authors: Quinn, S. D., Deas, L. A., Dalgarno, P. A., Hedley, G. J., Samuel, I. D.W., and Penedo, C.
College/School:College of Science and Engineering > School of Chemistry
Journal Name:Biophysical Journal
Publisher:Cell Press
ISSN (Online):1542-0086

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