J. Biol. Chem., Vol. 255, Issue 8, 3245-3247, Apr, 1980
Action spectra determined with tunable dye laser light for light- induced proton efflux and uptake in membrane vesicles of Halobacterium halobium
RV Greene, RE MacDonald and GJ Perrault
A new pigment from Halobacterium halobium has been previously described
which mediates the electrogenic extrusion of sodium ions when illuminated.
Using essentially monochromatic light (0.05 nm bandwidth), maximum activity
for this pigment occurred at 590 nm as monitored by passive proton uptake
in envelope vesicles. The uncoupler bis(hexafluoroacetonyl)-acetone did not
shift peak activity, but did increase passive proton influx. When the new
pigment (NaP590) bacteriorhodopsin, the well characterized proton pump, and
were compared at their respective wave-lengths of maximum activity, NaP590
required approximately 100-fold more energy to achieve saturation.