Photochemically induced charge separation occurring in bacteriorhodopsin. Detection by time-resolved dielectric loss

Time-resolved dielectric loss (TRDL) measurements are reported for the photochemical excitation of bacteriorhodopsin (bR) in solid films of Halobacterium halobium purple membranes. These measurements provide an independent confirmation for the existence of an important component of charge separation...

Full description

Saved in:
Bibliographic Details
Published in:Biophysical journal 1991-07, Vol.60 (1), p.1-7
Main Authors: McIntosh, A.R., Boucher, F.
Format: Article
Language:English
Subjects:
analysis
bacteriorhodopsin
Bacteriorhodopsins - metabolism
Bacteriorhodopsins - radiation effects
Biological and medical sciences
charge
Fundamental and applied biological sciences. Psychology
Halobacterium - metabolism
Halobacterium halobium
Kinetics
Light
Microwaves
Molecular biophysics
Photochemistry
purple membranes
Time Factors
Citations: Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:Time-resolved dielectric loss (TRDL) measurements are reported for the photochemical excitation of bacteriorhodopsin (bR) in solid films of Halobacterium halobium purple membranes. These measurements provide an independent confirmation for the existence of an important component of charge separation in these membranes after photochemical excitation. The separation of charge is detected by the absorption of microwave energy by the multilayer films of purple membranes in a microwave cavity during flash photolysis experiments. The TRDL method has the advantage of being sensitive to charge separation occurring in both oriented and unoriented films of purple membranes. One disadvantage is that the water content of the samples must be minimized, however, there is some absorbed water present in our electrodeposited solid film samples. To the best of our knowledge, TRDL measurements have not been reported previously for photochemical charge separation in biological membranes. It is significant that an early decay component of TRDL in the 20-microseconds time domain corresponds to the relaxation of the negative charge displacement photocurrent in oriented samples of purple membranes. In addition, a component of charge separation persists during the first several hundred microseconds of the bR photocycle.
ISSN:0006-3495
1542-0086
DOI:10.1016/S0006-3495(91)82025-2