The direction of light-induced pH changes of bacteriorhodopsin in purple membrane fragments at different pH’s and temperatures under continuous illumination

Abstract EN

During this work, the effect of pH on the photoactivity of bacteriorhodopsin in purple membrane fragments has been studied under continuous high light intensity.

The activity of bacteriorhodopsin at acidic pH was found to be more sensitive to temperature changes than it was at neutral or higher pH values.

At low pH and room temperature, bacteriorhodopsin in purple membrane fragments acidifies its medium in agreements with the order of events near neutral or higher pH values and room temperature and disagreement with its activity at acidic and lower temperature values.

On the other hand, at room temperature and physiological pH, this study is compatible with the fact that one hydrogen ion is transported across the purple membrane per one bacteriorhodopsin photocycled.

Beyond these conditions the behavior of bacteriorhodopsin becomes much more complex.