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Title: Photo-Induced Surface Potential Change of Bacteriorhodopsin Mutant D96N Measured by Scanning Surface Potential Microscopy

Abstract

We report the direct measurement of photoinduced surface potential differences of wild-type (WT) and mutant D96N bacteriorhodopsin (BR) membranes at pH 7 and 10.5. Atomic force microscopy (AFM) and scanning surface potential microscopy (SSPM) were used to measure the BR membrane with the extracellular side facing up. We present AFM and SSPM images of WT and mutant D96N in which the light-dark transition occurred in the mid-scan of a single BR membrane. Photosteady-state populations of the M state were generated to facilitate measurement in each sample. The photoinduced surface potential of D96N is 63 mV (peak to valley) at pH 10.5 and is 48 mV at pH 7. The photoinduced surface potential of WT is 37 mV at pH 10.5 and {approx}0 at pH 7. Signal magnitudes are proportional to the amount of M produced at each pH. The results indicated that the surface potentials were generated by photoformation of surface charges on the extracellular side of the membrane. Higher surface potential correlated with a longer lifetime of the charges. A mechanistic basis for these signals is proposed, and it is concluded that they represent a steady-state measurement of the B2 photovoltage.

Authors:
 [1];  [1];  [2];  [3];  [3];  [2]
  1. ORNL
  2. Syracuse University
  3. University of Connecticut
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1014209
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Physical Chemistry B; Journal Volume: 110; Journal Issue: 22
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; ATOMIC FORCE MICROSCOPY; LIFETIME; MEMBRANES; MICROSCOPY; MUTANTS; SURFACE POTENTIAL

Citation Formats

Lee, Ida, Greenbaum, Elias, Budy, Stephen, Hillebrecht, Jason R, Birge, Robert R, and Stuart, Jeffrey A. Photo-Induced Surface Potential Change of Bacteriorhodopsin Mutant D96N Measured by Scanning Surface Potential Microscopy. United States: N. p., 2006. Web. doi:10.1021/jp052948r.
Lee, Ida, Greenbaum, Elias, Budy, Stephen, Hillebrecht, Jason R, Birge, Robert R, & Stuart, Jeffrey A. Photo-Induced Surface Potential Change of Bacteriorhodopsin Mutant D96N Measured by Scanning Surface Potential Microscopy. United States. doi:10.1021/jp052948r.
Lee, Ida, Greenbaum, Elias, Budy, Stephen, Hillebrecht, Jason R, Birge, Robert R, and Stuart, Jeffrey A. Sun . "Photo-Induced Surface Potential Change of Bacteriorhodopsin Mutant D96N Measured by Scanning Surface Potential Microscopy". United States. doi:10.1021/jp052948r.
@article{osti_1014209,
title = {Photo-Induced Surface Potential Change of Bacteriorhodopsin Mutant D96N Measured by Scanning Surface Potential Microscopy},
author = {Lee, Ida and Greenbaum, Elias and Budy, Stephen and Hillebrecht, Jason R and Birge, Robert R and Stuart, Jeffrey A},
abstractNote = {We report the direct measurement of photoinduced surface potential differences of wild-type (WT) and mutant D96N bacteriorhodopsin (BR) membranes at pH 7 and 10.5. Atomic force microscopy (AFM) and scanning surface potential microscopy (SSPM) were used to measure the BR membrane with the extracellular side facing up. We present AFM and SSPM images of WT and mutant D96N in which the light-dark transition occurred in the mid-scan of a single BR membrane. Photosteady-state populations of the M state were generated to facilitate measurement in each sample. The photoinduced surface potential of D96N is 63 mV (peak to valley) at pH 10.5 and is 48 mV at pH 7. The photoinduced surface potential of WT is 37 mV at pH 10.5 and {approx}0 at pH 7. Signal magnitudes are proportional to the amount of M produced at each pH. The results indicated that the surface potentials were generated by photoformation of surface charges on the extracellular side of the membrane. Higher surface potential correlated with a longer lifetime of the charges. A mechanistic basis for these signals is proposed, and it is concluded that they represent a steady-state measurement of the B2 photovoltage.},
doi = {10.1021/jp052948r},
journal = {Journal of Physical Chemistry B},
number = 22,
volume = 110,
place = {United States},
year = {Sun Jan 01 00:00:00 EST 2006},
month = {Sun Jan 01 00:00:00 EST 2006}
}