Campus Event Calendar
Event Entry
What and Who
Layering of surface water: Implications for physical and biological systems
Prof. Dr. Armen Mulkidjanian
Fachbereich Physik, Universität Osnabrück und dem
Belozersky Institut für Physiko-Chemische Biologie der
Lomonossov-Universität Moskau
ZBI-Vortrag
AG 3
Expert Audience
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Date, Time and Location
Monday, 19 December 2005
16:00
-- Not specified --
46.1 - MPII
23
Saarbrücken
Abstract
The traits of water at the surface, especially at an electrically charged one, differ essentially from those in the bulk phase. The properties of surface water layers can be tackled in pulsed experiments with membrane enzymes. In such experiments, protons that are ejected (or captured) by light-triggered enzymes are traced on their way between the membrane surface and the bulk aqueous phase. In several laboratories it has been shown that proton exchange between the membrane surface and the bulk water phase proceeds with time as slow as 1 ms. The retardation owes to the interfacial barrier for electrically charged species. The magnitude of the barrier depends linearly on the electric charge of the penetrating ion and varies between 0.09 eV for /p/-nitrophenol and MES (with charge of -1) and more than 0.36 eV for pyranine (with charge of -4). For protons proper, the barrier height could be estimated as about 0.12 eV. In terms of ordinary electrostatics, the barrier could be ascribed to dielectric saturation of water at a charged surface. In terms of nonlocal electrostatics, the barrier could owe to dielectric overscreening in the surface water layers. The implications for the reactions at interfaces, especially those coupled with biological energy conversion and
membrane transport, as well for the modelling of such reactions would be discussed.
membrane transport, as well for the modelling of such reactions would be discussed.
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Veronika Weinand, 12/14/2005 14:49
Veronika Weinand, 12/14/2005 14:40 -- Created document.
Veronika Weinand, 12/14/2005 14:40 -- Created document.