• Bacteriorhodopsin

    measured on the SURFE2R N1

BR – pH dependence on the SURFE2R N1

BR pH dependence Slider

Icon N1   SURFE2R N1 data and applications:

Light induced currents have been measured at different pH values. Proton translocation depends on proton binding and release which show apparent pK values of > 10.5 and 4.9 respectively.

Author: Nanion Technologies, in cooperation with Dimitrios Fotiadis, University of Bern
Target (Synonyms): BR, Bacteriorhodopsin
Family / Type: Ion-translocating Microbial Rhodopsin Family (MRF, TCDB: 3.E.1)
Mode of transport: light-driven H+ pump
Organism: Halobacterium salinarum
Sample: purple membrane preparation
Expression: Native
Platform: SURFE2R N1

Background and Assay Description:
The membrane vesicles have been prepared at pH 7.5. After rinsing with solution of a given pH and incubating for 5 minutes to equilibrate the pH, we applied light pulses of 500 ms using LEDs with 470 nm wavelength and 100 mA to activate proton pumping in BR. The recorded currents clearly depend on pH, showing optimum pH close to pH 9 and down regulation at both, acidic and alkaline pH. Proton translocation is affected by pH dependent proton binding and release, which might be rate limiting at alkaline and acidic pH respectively. The apparent pK values for proton binding (>10.5) and release (4.9) were calculated from the fit of the pH dependent peak currents.

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