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Impressum
(c) 2002 BMO

"THz radiation from bacteriorhodopsin reveals correlated primary electron and proton transfer processes"
G. I. Groma, J. Hebling , I. Z. Kozma , G. Váró, J. Hauer, J. Kuhl, E. Riedle
Proc. Natl. Acad. Sci. USA 105, 6888 - 6893 (2008)


Abstract:
The kinetics of electrogenic events associated with the different steps of the light-induced proton pump of bacteriorhodopsin is well studied in a wide range of time-scales by direct electric methods. However, the investigation of the fundamental primary charge translocation phenomena taking place in the functional energy conversion process of this protein - as well as in other biomolecular assemblies utilizing light energy - has remained experimentally unfeasible, due to the lack of proper detection technique operating in the 0.1-20 THz region. Here we show that extending the concept of the familiar Hertzian dipole emission into the extreme spatial and temporal range of intramolecular polarization processes provides an alternative way to study ultrafast electrogenic events on naturally ordered biological systems. Applying a relatively simple experimental arrangement based on this idea, we were able to observe light-induced coherent terahertz radiation from bacteriorhodopsin with fs time-resolution. The detected THz signal was analyzed by numerical simulation in the framework of different models for the elementary polarization processes. It was found that the principal component of the THz emission can be well described by excited state intramolecular electron transfer within the retinal chromophore. An additional slower process is attributed to the earliest phase of the proton pump, probably occurring by the redistribution of a H-bond near the retinal. The correlated electron and proton translocation supports the concept assigning a functional role to the light-induced sudden polarization in retinal proteins.

BMO authors (in alphabetic order):
Jürgen Hauer
Ida Zsuzsanna Kozma
Eberhard Riedle

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Letzte Änderung: 2016-09-14 13:34