A PROTON RELEASE SITE ON THE C-TERMINAL SIDE OF BACTERIORHODOPSIN |
| |
| Authors: | Qingguo Li Rajni Govindjee Thomas G Ebrey† |
| |
| Institution: | Department of Physiology and Biophysics, 407 S. Goodwin, University of Illinois, Urbana, IL 61801, USA |
| |
| Abstract: | We have studied the pH dependence of the light-induced proton release and uptake by bacteriorhodopsin. The quantum efficiency of proton release in cell envelopes and proton uptake in phospholipid vesicles is high in the low pH range and begins to decline between pH 6 and 7 in cell envelopes and between pH 7–8 in phospholipid vesicles. In the cell envelope vesicles the proton release increases again above pH 8–8.5; in phospholipid vesicles a proton release is observed before proton uptake at pHs greater than 9. We suggest that the light-induced proton release observed at high pHs are due to protons released and rebound on the carboxyl terminal side of bacteriorhodopsin. |
| |
| Keywords: | |
|
|
