The effect of pH on proton transport by bacteriorhodopsin

Ormos, Pál; Hristova, Silvia; Keszthelyi, L.

doi:10.1016/0005-2728(85)90061-1

Cited by 27 publications

(20 citation statements)

References 16 publications

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“…In fact, these data support our previous observation on pH dependence of the microsecond phase amplitude in PM and the bR proteoliposomes [22,23]. Moreover, Ormos et al [28] did not ¢nd any changes in the microsecond components of the photocurrent measured in the oriented purple membrane at 4.5 6 pH 6 10.5. Liu [29], using the same photocurrent method, described a pH dependence of the microsecond component quite similar to ours.…”

Section: Resultssupporting

confidence: 91%

Photovoltage evidence that Glu‐204 is the intermediate proton donor rather than the terminal proton release group in bacteriorhodopsin

Kalaidzidis¹,

Belevich²,

Kaulen³

1998

FEBS Letters

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Electrogenic events in the E204Q bacteriorhodopsin mutant have been studied. A two-fold decrease in the magnitude of microsecond photovoltage generation coupled to M intermediate formation in the E204Q mutant is shown. This means that deprotonation of E204 is an electrogenic process and its electrogenicity is comparable to that of the proton transfer from the Schiff base to D85. pH dependence of the electrogenicity of M intermediate formation in the wild-type bacteriorhodopsin reveals only one component corresponding to the protonation of D85 in the bacteriorhodopsin ground state and transition of the purple neutral form into the blue acid form. Thus, the pK of E204 in the M state is close to the pK of D85 in the bacteriorhodopsin ground state ( 6 6 3) and far below the pK of the terminal proton release group (V6). It is concluded that E204 functions as the intermediate proton donor rather than the terminal proton release group in the bacteriorhodopsin proton pump.z 1998 Federation of European Biochemical Societies.

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Section: Resultssupporting

confidence: 91%

Photovoltage evidence that Glu‐204 is the intermediate proton donor rather than the terminal proton release group in bacteriorhodopsin

Kalaidzidis¹,

Belevich²,

Kaulen³

1998

FEBS Letters

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“…Unexpectedly, the polarity of this photovoltage was opposite to the proton-pumping direction. This result was confirmed by several laboratories measuring photocurrents (Hong and Montal, 1979;Ormos et a/., 1985;Okajima and Hong, 1986) or photovoltages (Skulachev, 1982;Trissl, 1983;Rayfield, 1985;Hristova eta/., 1986;Trissl and Gartner, 1987;Var6 and Bryl, 1988). The amplitude of the signal did not change with temperature in the range 110-300 K (Chamorovskii eta/., 1987;Kononenko eta/., 1987) and persisted upon drying the purple membranes (Kovacs and Dioumaev and Keszthelyi, 1988;Var6 and Bryl, 1988).…”

Section: The Primary Eventmentioning

confidence: 57%

Photoelectric Measurements of Membranes

Trissl

1990

Photochem & Photobiology

137

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“…Some previous reports on the pH independency of some of the kinetic steps in the BR photocycle (e.g., the decay of M) did not include data at high enough pH (Holz et al, 1989). Several reports [e.g., on the increase in the decay rate for M' and the prominent decrease for MS with pH (Ormos et al, 1985;Kouyama et al, 1988)] contain data similar to ours: others are to various extents in conflict (Konishi & Packer, 1978: Hanamoto et al, 1984. When the step in question is identified as the deprotonation or reprotonation of the Schiff base or a protein residue, it is tempting to attribute observed pH effects to the ionization of the proton acceptor or donor groups.…”

Section: Discussionmentioning

confidence: 99%

Pathways of the rise and decay of the M photointermediate(s) of bacteriorhodopsin

Váró¹,

Lanyi²

1990

Biochemistry

152

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The photocycle of bacteriorhodopsin (BR) was studied at alkaline pH with a gated multichannel analyzer, in order to understand the origins of kinetic complexities in the rise and decay of the M intermediate. The results indicate that the biphasic rise and decay kinetics are unrelated to a photoreaction of the N intermediate of the BR photocycle, proposed earlier by others [Kouyama et al. (1988) Biochemistry 27, 5855-5863]. Rather, under conditions where N did not accumulate in appreciable amounts (high pH, low salt concentration), they were accounted for by conventional kinetic schemes. These contained reversible interconversions, either M in equilibrium with N in one of two parallel photocycles or L in equilibrium with as well as M in equilibrium with N in a single photocycle. Monomeric BR also showed these kinetic complications. Conditions were then created where N accumulated in a photo steady state (high pH, high salt concentration, background illumination). The apparent increase in the proportion of the slow M decay component by the background illumination could be quantitatively accounted for with the single photocycle model, by the mixing of the relaxation of the background light induced photo steady state with the inherent kinetics of the photocycle. Postulating a new M intermediate which is produced by the photoreaction of N was neither necessary nor warranted by the data. The difference spectra suggested instead that absorption of light by N generates only one intermediate, observable between 100 ns and 1 ms, which absorbs near 610 nm. Thus, the photoreaction of N resembles in some respects that of BR containing 13-cis-retinal.

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The effect of pH on proton transport by bacteriorhodopsin

Cited by 27 publications

References 16 publications

Photovoltage evidence that Glu‐204 is the intermediate proton donor rather than the terminal proton release group in bacteriorhodopsin

Photovoltage evidence that Glu‐204 is the intermediate proton donor rather than the terminal proton release group in bacteriorhodopsin

Photoelectric Measurements of Membranes

Pathways of the rise and decay of the M photointermediate(s) of bacteriorhodopsin

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