title: Mechanisms of pulse response and differential response of bacteriorhodopsin and their relations.
abstract: Bacteriorhodopsin (BR) films are oriented and deposited on indium tin oxide conductive glass by using electrophoretic sedimentation and Langmuir-Blodgett methods to construct sandwich-type photocells, respectively. The pulse response photoelectric signal of the BR photocell under pulsed laser and the differential response photoelectric signal under irradiation of interval light are measured. The origins of these two types of photoelectric responses and their correlations are analyzed. The pulse response signal initiates from the ultrafast charge separation of the retinal and the proton translocation followed by the deprotonation and reprotonation of the Schiff base and its surrounding amino acids. This is a quick response and is the preceding reaction of the differential response. The differential response signal is caused by the charging and discharging of the continuous proton current of the BR light-driven proton pump at light-on and light-off, which is a slow process. The differential response is related to not only the construction of the BR photocell but also the coupling mode of measurement. To observe the differential response signal, the BR photocell must have large enough B3 and B3' components in its pulse response as well as an alternative coupling mode to measure it.
authors.affiliation: State Key Laboratory of Transient Optics Technology, Xi'an Institute of Optics and Precision Mechanics, Chinese Academy of Sciences, Xi'an, People's Republic of China. yaobl@opt.ac.cn
authors.forename: Baoli
authors.initials: B
authors.lastname: Yao
authors.forename: Yingli
authors.initials: Y
authors.lastname: Wang
authors.forename: Kunsheng
authors.initials: K
authors.lastname: Hu
authors.forename: Deliang
authors.initials: D
authors.lastname: Chen
authors.forename: Yuan
authors.initials: Y
authors.lastname: Zheng
authors.forename: Ming
authors.initials: M
authors.lastname: Lei
mesh_terms: D001436:Bacteriorhodopsins / Q000378:metabolism* / Q000528:radiation effects*; D019617:Halobacterium salinarum; D007834:Lasers; D008027:Light; D010777:Photochemistry; D011522:Protons; D018717:Purple Membrane / Q000528:radiation effects
chemical_list: D011522:Protons; D001436:Bacteriorhodopsins