Stuttgart 2012 – scientific programme
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MO: Fachverband Molekülphysik
MO 17: Femtosecond Spectroscopy IV
MO 17.2: Talk
Thursday, March 15, 2012, 11:00–11:15, V38.03
Ultrafast Chromophore Dynamics in Xanthorhodopsin — •Miriam Colindres1, Melanie Geier2, Ilka Haferkamp2, Ekkehard Neuhaus2, and Rolf Diller1 — 1Physics Department, University Kaiserslautern, Germany — 2Biology Department, University Kaiserslautern, Germany
Xanthorhodopsin from the extreme halophile eubacterium Salinibacter ruber is one of the simplest bioenergetic systems for collecting light using excited state energy transfer. This member of the retinal protein family is a light driven transmembrane proton pump (SX) (1). We present the first results of ultrafast vibrational dynamics on a sub-ps time scale of the primary photoreaction in xanthorhodopsin. Our experiments show evidence for the proton-pump cycle initiated by Ret isomerization after excitation of SX. The Ret S1 surface branches into the hot J-state and the hot all-trans-Ret, followed by vibrational cooling and torsional relaxation of J-state and all-trans-Ret. Our results suggest a prolonged protein response compared to bacteriorhodopsin. The protein relaxes slower than in BR (11 ps) (2) and the perturbation of protein is permanent on the experimental time scale. In this context the excited state dynamics of SX as a sensor for protein dynamics are of particular interest. Therefore we are currently investigating the vibrational modes of SX in the carbonyl region between 1700 and 1800 cm−1.
(1) J. Antón et al., IUMS, 52, 485-491 (2002)
(2) R. Groß et al., J. Am. Chem. Soc., 131, 14868-14878 (2009)