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Dresden 2003 – scientific programme

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SYSE: Simulation and experiment

SYSE 2: Poster (gemeinsam mit SYCN und CPP)

SYSE 2.4: Poster

Tuesday, March 25, 2003, 19:00–21:00, ZEU/250

Stability of the Protonated State of Rhodopsin Chromophore — •Minoru Sugihara1, Peter Entel1, Volker Buss2, and Jürgen Hafner31Institute of Physics, University of Duisburg, Duisburg, 47048 Duisburg, Germany — 2Institute of Chemistry, University of Duisburg, Duisburg, 47048 Duisburg, Germany — 3Center for Computational Material Science, University of Vienna, 1090 Vienna, Austria

The chromophore of rhodopsin is 11-cis-retinal which is bound via a protonated Schiff base (pSb) linkage with Lys296. The counterion, Glu113, providing the neutralizing negative charge. The chromophore stays protonated throughout the visual cycle until meta II, the so-called signaling state, is reached and the proton is transferred from the chromophore to the counterion. The nature of the Sb counterion interaction in the ground state of rhodopsin has been a focus of many previous researches. The recent x-ray structure of rhodopsin by Palczewski et al [1] has revealed that the side chain of Glu113 is located in the vicinity of the Schiff base nitrogen, suggesting a direct contact between them but from the crystal structure mechanism of pSb stabilization is not entirely clear. We have investigated a minimal model for the salt bridge base on the x-ray coordinate. Different configurations were studied with molecular dynamics using the Vienna ab initio simulation package (VASP) and conclude that threonine94, the Glu113 in a hydrogen bond network, plays a critical role in stabilizing the protonated status of the chromophore in rhodopsin. [1] K. Palczewski et al. Science 289 (2000) 739.

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