An Apparent General Solution for the Kinetic Models of the Bacteriorhodopsin Photocycles

Hendler, Richard W.

doi:10.1021/jp052733h

Cited by 15 publications

(53 citation statements)

References 51 publications

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“…Table 2 shows the presence of 6 kinetically distinct species with taus near 0.008, 0.05, 0.15, 0.5, 1.9, and 4.9 ms. These are essentially the same components as obtained previously by Hendler et al [14,20] and Chizhov et al [21] using optical data, and by Rodig et al [22] and Morgan et al [23 ] using FTIR data, and by Müller et al using both optical and FTIR data [24]. It is also shown in Table 2 that the component seen optically with a tau near 1.9 ms is absent in the electrical data.…”

Section: Discussionsupporting

confidence: 86%

“…In one there is a single photocycle with reversible steps emanating from a homogeneous ground state, while the other has two or more independent photocycles originating from different forms of BR. It is outside the scope of this paper to present the evidence for both views, but a general review of the situation can be found in reference [20].…”

Section: Discussionmentioning

confidence: 99%

“…Based on the parallel cycles model favored by Hendler et al [14,20] at pH near 7 and temperature near 20 °C there are two separate cycles, one containing M f and the other M s .…”

Section: Discussionmentioning

confidence: 99%

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Simultaneous measurements of fast optical and proton current kinetics in the bacteriorhodopsin photocycle using an enhanced spectrophotometer

Kakareka

Smith

Pohida

et al. 2008

Journal of Biochemical and Biophysical Methods

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A one-of-a-kind high speed optical multichannel spectrometer was designed and built at NIH and described in this journal in 1997 [Cole et al. Vol 35,. The most unique aspect of this instrument was the ability to follow an entire time course from a single activation using a single sample. The instrument has been used to study rapid kinetic processes in the photon-driven bacteriorhodopsin photocycle and electron transport from cytochrome c to cytochrome aa 3 and from cytochrome aa 3 to oxygen. The present paper describes a second generation instrument with a number of important enhancements which significantly improve its capabilities for multichannel kinetic studies. An example application is presented in which the kinetics of photon-induced proton flow across the biological membrane is measured simultaneously with the individual steps of the photocycle determined optically. Matching the time constants for the two processes indicates which molecular transformations are associated with major proton movements.

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Section: Discussionsupporting

confidence: 86%

Section: Discussionmentioning

confidence: 99%

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Simultaneous measurements of fast optical and proton current kinetics in the bacteriorhodopsin photocycle using an enhanced spectrophotometer

Kakareka

Smith

Pohida

et al. 2008

Journal of Biochemical and Biophysical Methods

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“…These are essentially the same components as obtained previously by us (2,8) B. Electric Data-The raw data for proton currents generated by actinic pulses of different strengths are shown in the range of 0 to 1 ms in Figure 3 and from 0 to 8 ms in Figure 4.…”

Section: Saturation Behaviorssupporting

confidence: 62%

“…The relative amount of total apparent voltage for this transition was about 7% (Table 4). A tau near 5 ms is shared by both cycles for the reformation of the ground state (2,8). As shown in Table 4, the transition with a tau of 5.1 ms accounted for about 63% of the total apparent voltage formation.…”

Section: Discussionmentioning

confidence: 90%

Electrogenic Proton-Pumping Capabilities of the M-Fast and M-Slow Photocycles of Bacteriorhodopsin

Hendler

Meuse

2008

Biochemistry

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The parallel model for the bacteriorhodopsin (BR) photocycle at neutral pH and a temperature near 20 °C contains an M-fast cycle with steps BR → K → L → M f → N → O → BR and an M-slow cycle which contains steps BR → K → L → M s → BR. With increasing actinic laser strength, the M-fast cycle at first rises faster than the M-slow cycle, but reaches saturation sooner and at a lower level than the M-slow cycle. The O-intermediate shows the same saturation behavior as M f . In this paper, we show that the peak current of proton flux and the apparent voltages developed by this flux show the same saturation behavior as M s , which is very different from that of both M f and O. It is further shown that most of the proton-charge displacement is connected with the step M s → BR. The optical and electrical data in these studies were collected simultaneously by a newly designed and built spectrometer which is described separately.Kinetic analyses of bacteriorhodopsin (BR 1 ) photocycle data have led to two distinctly different kinds of models (1). In one there is a single photocycle with reversible steps emanating from a homogeneous ground state, while the other has two or more independent photocycles originating from different forms of BR. While the single photocycle model is much more widely accepted, our laboratory has long been a subscriber to a model involving parallel photocycles. In a recent publication (2), the evidence for both kinds of models was presented in some detail, as well as the reasons for our favoring the parallel photocycle model.The parallel photocycle for BR at pH near 7 and temperature near 20 °C consists of two separate cycles, one containing M f and the other M s . † This research was supported by the Intramural Research Program of the NIH, National Heart, Lung, and Blood Institute. ‡ Certain commercial equipment, instruments, or materials are identified in this paper to foster understanding. Such identification does not imply recommendation or endorsement by the National Institutes of Health or the National Institute of Standards and Technology, or that the materials and equipment are necessarily the best available for the purpose. NIH Public Access Author ManuscriptBiochemistry. Author manuscript; available in PMC 2009 May 11. Published in final edited form as:Biochemistry. where K, L, M, N, and O are the recognized intermediates of the BR photocycle and the subscripts "f" and "s" indicate the faster and slower time constants for intermediates displaying the same characteristic spectra. The maximum characteristic absorbance wavelengths for these individual spectra are listed in Using the procedures of Kesthelyi and Dér and their collaborators (4,5), one can measure the proton current which flows during a single turnover of BR. This is accomplished by orienting the purple membrane (PM) in an electric field in an optical cuvette and holding this orientation by forming an acyrlamide gel of the oriented population. The current is measured using two platinized electrodes and a suitable amplifi...

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Effect of Xenon Binding to a Hydrophobic Cavity on the Proton Pumping Cycle in Bacteriorhodopsin

Hayakawa

Kasahara

Hasegawa

et al. 2008

Journal of Molecular Biology

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An Apparent General Solution for the Kinetic Models of the Bacteriorhodopsin Photocycles

Cited by 15 publications

References 51 publications

Simultaneous measurements of fast optical and proton current kinetics in the bacteriorhodopsin photocycle using an enhanced spectrophotometer

Simultaneous measurements of fast optical and proton current kinetics in the bacteriorhodopsin photocycle using an enhanced spectrophotometer

Electrogenic Proton-Pumping Capabilities of the M-Fast and M-Slow Photocycles of Bacteriorhodopsin

Effect of Xenon Binding to a Hydrophobic Cavity on the Proton Pumping Cycle in Bacteriorhodopsin

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