Cooperativity‐regulated parallel pathways of the bacteriorhodopsin photocycle

FEBS Letters

Tokaji, Zsolt¹ 

[1]Institute of Biophysics, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, PO Box 521, H-6701 Hungary

关键词: Kinetic difference;    Kinetics of N;    Light intensity dependence;    Photocycle model;    Proton translocation mechanism;    BR;    bacteriorhodopsin;    Mf;    Ms and N;    intermediates of the photocycle;    M f;    rapidly decaying component of the M intermediate;    M s;    slowly decaying component of the M intermediate;    Mf and Ms;    subforms of the Ms intermediate;   

DOI  :  10.1016/0014-5793(94)01344-Z

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The paper demonstrates that the actinic light density dependence of the millisecond part of the bacteriorhodopsin (BR) photocycle at high pH predicts a model, which is the same in the sequence of the intermediates as concluded previously on the basis of double flash experiments [1992, FEBS Lett. 311, 267–270]. This model consists of the M_f→N→BR and M_s→BR parallel pathways, the relative yields of which are regulated by cooperative interaction of the BR molecules. The decay of M_s is always slower than the decay of M_f and described as a direct reprotonation of the Schiff-base from the bulk, and the recovery of the ground-state nearly at the same time. M_s is decomposed into M′_f and M′_s. The first does not reprotonate, and similarly to M_f, it is suggested to be before the conformational change (switch), which latter process would be just before the decay of M_f. A simple way for the determination of the kinetics is also used. This confirms that the amount of N decreases with increasing fraction cycling and shows that the decay rate of N is independent of the fraction cycling. The differences in the kinetics are compared to each other, and they seem to allow a new way of kinetic evaluation at least under special conditions. The aim of this paper was briefly explained in my poster presented on the VIth International Conference on Retinal Proteins (see [14]).

【 授权许可】

Unknown