71
Modeling of Biomolecular Systems Interactions, Dynamics, and Allostery Poster Session I
17-POS
Board 17
Ab-Initio Molecular Dynamics Simulation of Photoacids: Competition between Excited
State Proton and OH
-
Transport via a Water Wire
Gül Bekcioglu
, Christoph Allolio, Daniel Sebastiani.
Department of Chemistry , Halle (Saale), Germany.
Biophysical processes often take place based on proton relay along a hydrogen bonded chain [1].
Such proton transfer reactions along "water wires" are difficult to observe directly inside a
protein. Photosensitive acid/base systems provide a method to control and study ultrafast proton
transport via infrared spectroscopy [2]. Hydroxyquinolones (HQ), are simultaneously photoacids
and photobases.
We elucidate excited state proton exchange mechanisms along short chains of water molecules
(water wires) by means of ab-initio calculations. We exploit the specific geometry of 7-
Hydroxyquinoline, a combined photoacid/-base, to establish well-defined proton donor/acceptor
sites, linked by a water wire of three water molecules [3]. In addition, departing from our
successful simulation of the excited state dynamics and fluorescence shift of the related N-
methyl-6-quinolone [4], we also study the ground and excited state aqueous solvation of different
HQs, focussing on the identification of water wires and excited state protonation dynamics.
[1] H. Luecke, H.-T. Richter, J. K. Lanyi, Science 280 (1998), 1934.
[2] O. F. Mohammed, D. Pines, J. Dreyer, E. Pines and E. T. J. Nibbering., Science 310 (2005),
5745.
[3] G. Bekcioglu, C. Allolio, and D. Sebastiani (submitted).
[4] C. Allolio, M. Sajadi, N. P. Ernsting and D. Sebastiani, Angew. Chem. Int. Ed. 52 (2013),
1813-1816.
