EFFECTS OF THE REMOVAL OF THE CARBOXYL TERMINAL TAIL OF BACTERIORHODOPSIN(BR) BY PAPAIN DIGESTION ON THE PHOTOCYCLE AND PROTON PUMPING
酶切菌紫质(bR)C端对紫膜光循环和质子泵效率的影响

The photocycle characteristics and proton pumping efficiency of purpleme-mbrane suspension with the C-terminal of BR digested by papain proteolysis in low salt concentration were studied. It was found that the slow dcay component M5 of intermediate Mm was reduceb dy 20%, the intermediate O640 by 50%, and the proton pumping efficiency was reduced by 70%.The response to the second flash after a first flash in a different time gap showed that the period of photocycle did not change. All these results indicate that the proton pumping efficiency change caused by the enzyme digestion dosen't coinc'de with hte photocycle intermediate change.The ionic strength has different influences on normal and papain-treated purple membrane. It suggests that there is a different conformation of C-terminal which is essential for proton pumping in different salt concentration.