Bacteriorhodopsin as a possible chloride pump

Abstract
Purple membranes oriented and immobilized in gel show charge transfer at pH 0.55 if the pH is set by HCl. Current appears as laser flash driven transient and also as continuous current by quasi‐continuous illumination. If the pH value 0.55 is set by H2SO4 continuous current is not observed. The results suggest that bacteriorhodopsin may pump chloride ions at low pH.