Coupling between the bacteriorhodopsin photocycle and the protonmotive force in Halobacterium halobium cell envelope vesicles. II. Quantitation and preliminary modeling of the M----bR reactions.
Coupling between the bacteriorhodopsin photocycle and the protonmotive force in Halobacterium halobium cell envelope vesicles. II. Quantitation and preliminary modeling of the M----bR reactions.
复制标题
盐杆菌细胞包膜囊泡中细菌视紫红质光循环与质子动力之间的耦合。
DOI：
10.1016/s0006-3495(84)84243-5
复制
发表时间：
1984
影响因子：
3.4
通讯作者：
Stoeckenius,W
中科院分区：
文献类型：
--
作者：
Groma,GI;Helgerson,SL;Wolber,PK;Beece,D;Dancshazy,Z;Keszthelyi,L;Stoeckenius,W
halobium halobium （H. halobium）的细胞膜含有质子泵细菌视紫红质，它可以产生光驱动的跨膜质子动力。研究了细菌视紫红质光循环与质子动力电势组分的相互作用。采用超声法制备了盐藻细胞包膜囊泡，并在Ficoll/NaCl/CsCl密度梯度下进行了超离心纯化。在连续光照（550 +/- 50 nm）从0到40 mW cm-2变化的情况下，囊泡保持0到-100 mV的膜电位。膜电位通过3H-TPMP+摄取的流动透析测定，并可被解耦剂羰基氰化物-间氯苯腙消除。采用时间分辨吸收光谱法测量M光循环中间体在弱激光（588 nm）照射下的衰变动力学，同时连续照射囊泡。用计算机反褶积程序拟合了两个指数衰减的M衰变动力学。随着背景光强度的增加，快速衰减形式的幅度减小（占总量的70% ~ 10%），而较慢衰减形式的幅度和寿命增加（23 ~ 42 ms）。尽管膜电位与细菌视紫红质光周期m型之间的任何关联都是复杂的，但目前的数据将允许对这种相互作用的物理机制进行设计和实施的具体测试。
The cell membrane of Halobacterium halobium (H. halobium) contains the proton-pump bacteriorhodopsin, which generates a light-driven transmembrane protonmotive force. The interaction of the bacteriorhodopsin photocycle with the electric potential component of the protonmotive force has been investigated. H. halobium cell envelope vesicles have been prepared by sonication and further purified by ultracentrifugation on Ficoll/NaCl/CsCl density gradients. Under continuous illumination (550 +/- 50 nm) varied from 0 to 40 mW cm-2, the vesicles maintain a membrane potential of 0 to -100 mV. The membrane potential was measured by flow dialysis of 3H-TPMP+ uptake and could be abolished by the uncoupler carbonylcyanide-m-chlorophenylhydrazone. Time-resolved absorption spectroscopy was used to measure the decay kinetics of the M photocycle intermediate, which was initiated by a weak laser flash (588 nm), while the vesicles were continuously illuminated as above. The M decay kinetics were fitted with two exponential decays by a computer deconvolution program. The faster decaying form decreases in amplitude (70 to 10% of the total) and the slower decaying form increases in amplitude and lifetime (23 to 42 ms) as the background light intensity increases. Although any correlation between the membrane potential and the bacteriorhodopsin photocycle M-forms is complex, the present data will allow specific tests of the physical mechanism for this interaction to be designed and conducted.