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25 May 2004 Voltage-induced "gating" of bacterial porin as reversible protein denaturation
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Proceedings Volume 5467, Fluctuations and Noise in Biological, Biophysical, and Biomedical Systems II; (2004)
Event: Second International Symposium on Fluctuations and Noise, 2004, Maspalomas, Gran Canaria Island, Spain
General porin OmpF forms water-filled channels in the outer membrane of E. coli bacteria. When reconstituted into planar bilayer lipid membranes, these channels can be closed (or “gated”) by high electric fields. We discover that: (i) channel gating is sensitive to the type of cations in the membrane-bathing solution according to their position in the Hofmeister series; (ii) channel gates to a “closed” state that is represented by a set of multiple sub-conformations with at least three distinctly different conformations contributing to the closed-state conductance histogram. Taken together with the nearly symmetric response to the applied voltage of changing polarity and the hysteresis phenomena reported previously by others and reproduced here, these findings suggest that the voltage-induced closure of the OmpF channel is a consequence of reversible denaturation of the protein by the high electric field. If so, the voltage-induced gating of bacterial porins can serve as an instructive model to study the physics of protein folding at the single-molecule level.
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Ekaterina M. Nestorovich and Sergey M. Bezrukov "Voltage-induced "gating" of bacterial porin as reversible protein denaturation", Proc. SPIE 5467, Fluctuations and Noise in Biological, Biophysical, and Biomedical Systems II, (25 May 2004);

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