This paper is part of the Proceedings of the 13th International Conference on Retinal Proteins, Barcelona, Spain, 15–19 June 2008.
Excitation of the M Intermediates of Bacteriorhodopsin†
Article first published online: 13 FEB 2009
© 2009 The Authors. Journal Compilation. The American Society of Photobiology
Photochemistry and Photobiology
Volume 85, Issue 2, pages 609–613, March/April 2009
How to Cite
Tóth-Boconádi, R., Dér, A., Fábián, L., Taneva, S. G. and Keszthelyi, L. (2009), Excitation of the M Intermediates of Bacteriorhodopsin. Photochemistry and Photobiology, 85: 609–613. doi: 10.1111/j.1751-1097.2008.00521.x
- Issue published online: 25 FEB 2009
- Article first published online: 13 FEB 2009
- Received 15 August 2008, accepted 14 November 2008
Protein electric response signals (PERS) of the M intermediates of wild-type bacteriorhodopsin (bR) were recorded. Contrary to earlier findings reporting on a single-phase response upon excitation of the M intermediates, a kinetic analysis of the signals revealed the existence of three components, the fastest and the slowest ones of negative, while the middle one of positive sign with respect to the normal direction of proton pumping. Based on proton motion indicator experiments and molecular dipole calculations, the components were assigned to proton transfer steps and conformational changes driving the bR molecule back from the M to the ground state upon blue light excitation. The fastest, negative pump component was assigned to the proton transfer from D85 to the Schiff base. The subsequent positive component was attributed to rearrangements in the protein core (in the vicinity of the retinal molecule), triggered by the primary proton transfer process. The slowest component was established to reflect charge rearrangements associated with proton uptake by the protein from the bulk.