&lt;title&gt;Electrostriction of purple membranes and the model of active proton transfer in bacteriorhodopsin&lt;/title&gt;

Kietis, Povilas Bronius; Saudargas, Paulius; Valkūnas, Leonas

doi:10.1117/12.515645

Cited by 2 publications

(5 citation statements)

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“…Our previous experimental observations revealing that in the ground state the PM film exposes the polarization electric field directed towards the extra-cellular side confirm this conclusion [34]. Manifestation of direct and inverse piezoelectric effects [63] as well as electrostrictive properties of BR [34,46,51,59] are also in line with those conclusions. The presented mechanism of the active proton pumping in BR is reasoned by our experimental observations of photo-response and electro-acoustic studies, the piezoelectric concept, recent molecular dynamics simulations [27][28][29][30][31], and X-ray crystallographic data [9][10][11][12].…”

Section: Generalsupporting

confidence: 70%

“…The PERS experimental results were obtained by averaging 50 separate photoresponses. A detailed description of the PERS measurement is presented elsewhere [34,46,59].…”

Section: Photoresponsementioning

confidence: 99%

“…Electrical studies were performed on dried purple membrane samples [38][39][40], on BR proteoliposomes, on BR adsorbed to millipore filters [41], and on BR incorporated into planar lipid membranes [42][43]. In recent years, studies of the photocurrent in purple membranes have also been carried out [44][45][46]. The photoelectric response signal (PERS) of the oriented BR samples was investigated under various conditions [46][47][48][49][50][51].…”

Section: Introductionmentioning

confidence: 99%

“…In recent years, studies of the photocurrent in purple membranes have also been carried out [44][45][46]. The photoelectric response signal (PERS) of the oriented BR samples was investigated under various conditions [46][47][48][49][50][51]. The effect of the external electric field on the rate constants of the PERS was also assigned [48].…”

Section: Introductionmentioning

confidence: 99%

“…Herein we propose the modified version of the physical model of the proton transfer in BR [34] based on our new experimental results (see also [46,51,64] and the newest structural knowledge of the protein and its changes during the photocycle [15,16,24]. The height of an energy barrier between the Schiff base (SB) and Asp85 in BR decreases after photon absorption thus initiating the first step in proton pumping.…”

Section: Introductionmentioning

confidence: 99%

See 4 more Smart Citations

Piezoelectric model for active proton transport in bacteriorhodopsin

Kietis¹,

Saudargas²,

Valkūnas³

2005

Lith. J. Phys.

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Bacteriorhodopsin is a photoactive protein performing the transmembrane proton pumping through the purple membrane of Halobacterium salinarum. Experimental results of the electrical studies of the dried purple membrane films excited by short light pulses are presented. The time constant of the photoelectric response of the purple membrane film corresponds to the optically detectable L intermediate lifetime that is tens of micro seconds. Absence of the positive part of the photoelectric response signal in the time range of tens of microseconds under acidic conditions supports the assumption about the possibility of blockage of the proton transfer. The polarization field is a stimulating factor of the active proton transfer according to the assumption of the suggested two-state model. The mechanical-electrical properties of the dipole materials and the piezoelectric effect of the hydrogen bonds are discussed in the context of the zwitterionic state of the Schiff base and its counter ion Asp85. On the basis of the recent crystallographic data and molecular dynamics simulations it is concluded that the polarization of the Schiff base is a consequence of the mechanically strained hydrogen bonds caused by the retinal photoisomerization. The reorganized H-bond network impedes the proton way back, and the proton accomplishes work while moving in the external circuit.

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Section: Generalsupporting

confidence: 70%

“…The PERS experimental results were obtained by averaging 50 separate photoresponses. A detailed description of the PERS measurement is presented elsewhere [34,46,59].…”

Section: Photoresponsementioning

confidence: 99%