Further Characterization of Anesthetic‐treated Purple Membranes

Henry, Nathalie; Beaudoin, Normand; Baribeau, Johanne; Boucher, François

doi:10.1111/j.1751-1097.1988.tb02698.x

Cited by 16 publications

(13 citation statements)

References 14 publications

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“…The red form was also found in vesicles reconstituted with soybean phosphatidylcholine (pK, = 7.5; Lozier et al, 1976;Hwang & Stoeckenius, 1977). That only the trans isomer can form the 480-nm species is shown with native purple membrane (Pande et al, 1989b;Henry et al, 1988) or with bR mutants (Mogi et al, 1989).…”

mentioning

confidence: 96%

Effect of a light-induced pH gradient on purple-to-blue and purple-to-red transitions of bacteriorhodopsin

Nasuda-Kouyama¹,

Fukuda²,

Iio³

et al. 1990

Biochemistry

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Bacteriorhodopsin-containing vesicles that were able to alkalize the extravesicular medium by greater than 1.5 pH units under illumination, i.e., inside-out vesicles, were reconstituted by reverse-phase evaporation with Halobacterium halobium polar lipids or exogenous phospholipids. Acid titration of a dark-adapted sample was accompanied by a color change from purple to blue (pKa = 2.5-4.5 in 0.15 M K2SO4), and alkali titration resulted in the formation of a red species absorbing maximally at 480 nm (pKa = 7 to greater than 9), the pKa values and the extents of these color changes being dependent on the nature of lipid. When a vesicle suspension at neutral or weakly acidic pH was irradiated by continuous light so that a large pH gradient was generated across the membrane, either a purple-to-blue or a purple-to-red transition took place. The light-induced purple-to-red transition was significant in an unbuffered vesicle suspension and correlated with the pH change in the extravesicular medium. The result suggests that the purple-to-red transition is driven from the extravesicular side, i.e., from the C-terminal membrane surface. In the presence of buffer molecules outside, the dominant color change induced in the light was the purple-to-blue transition, which seemed to be due to a large decrease in the intravesicular pH. But an apparently inconsistent result was obtained when the extravesicular medium was acidified by a HCl pulse, which was accompanied by a rapid color change to blue. We arrived at the following explanation: The two bR isomers, one containing all-trans-retinal and the other 13-cis-retinal, respond differently to pH changes in the extravesicular and the intravesicular medium. In this relation, full light adaptation was not achieved when the light-induced purple-to-blue transition was significant; i.e., only the 13-cis isomer is likely to respond to a pH change at the N-terminal membrane surface.

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mentioning

confidence: 96%

Effect of a light-induced pH gradient on purple-to-blue and purple-to-red transitions of bacteriorhodopsin

Nasuda-Kouyama¹,

Fukuda²,

Iio³

et al. 1990

Biochemistry

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“…Earlier work in this laboratory showed that pure lipid-free, detergent-free bacteriorhodopsin is not a purple but a red pigment with a maximum absorbance at 480 nm and a cyclic photochemical activity, including a 535 nm K-like intermediate and a 385 nm deprotonated M-like intermediate (Baribeau and Boucher, 1985). A similar 480 nm spectral form with a 385 nm M intermediate was also found for purple membrane in the presence of halogenated general anesthetics (Nishimura et al, 1985;Henry et al, 1988). In fact, the equilibrium between the 570 nm and 480 nm forms of bacteriorhodopsin is an acid-base equilibrium that appears under a wide variety of experimental conditions.…”

Section: Introductionmentioning

confidence: 60%

“…There are at least two reasons for this. One is that the absorbances changes ratio (A&AM:AAbR) is smaller in bR480 than in bR570 (Henry et al, 1988), and the other resides in the fact that bR480 has a K intermediate with maximum absorbance near 535 nm (Baribeau and Boucher, 1985), which enables effective photostationary equilibration between bR and K during the 10-ns, 532-nm flash, resulting in the formation of less M intermediate. The second point is that the 50 ms component that we report here for the M decay step in bR480 is not the slowest one that we have observed.…”

Section: Resultsmentioning

confidence: 99%

“…Transient bacteriorhodopsin absorption changes were measured with a set-up described elsewhere (Henry et al, 1988). The actinic light pulse was the 532-nm, 10-ns, 20-mJ pulse of a Q-switched Nd-YAG laser (Laser System 2000; JK Lasers, Rugby, England), and the analysis beam was detected with a 5-ns rise time photodiode protected from scattered actinic light by a high-attenuation 532-nm Raman holographic filter and a narrow interference filter.…”

Section: Photochemical H+ Pumping Activity and Photoelectrical Measmentioning

confidence: 99%

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Reversible inhibition of proton release activity and the anesthetic-induced acid-base equilibrium between the 480 and 570 nm forms of bacteriorhodopsin

Boucher¹,

Taneva²,

Elouatik³

et al. 1996

Biophysical Journal

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In purple membrane added with general anesthetics, there exists an acid-base equilibrium between two spectral forms of the pigment: bR570 and bR480 (apparent pKa = 7.3). As the purple 570 nm bacteriorhodopsin is reversibly transformed into its red 480 nm form, the proton pumping capability of the pigment reversibly decreases, as indicated by transient proton release measurements and proton translocation action spectra of mixture of both spectral forms. It happens in spite of a complete photochemical activity in bR480 that is mostly characterized by fast deprotonation and slow reprotonation steps and which, under continuous illumination, bleaches with a yield comparable to that of bR570. This modified photochemical activity has a correlated specific photoelectrical counterpart: a faster proton extrusion current and a slower reprotonation current. The relative areas of all photocurrent phases are reduced in bR480, most likely because its photochemistry is accompanied by charge movements for shorter distances than in the native pigment, reflecting a reversible inhibition of the pumping activity.

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“…Kinetics of proton exchange by bR were measured by the concentration differences of the M-412 intermediate of the photocycle (Henry et al 1988). …”

Section: Methodsmentioning

confidence: 99%

Light adaptation of bacteriorhodopsin in the presence of valinomycin and potassium. pH-dependence

1988

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In the presence of valinomycin and K(+), bacteriorhodopsin undergoes (i) a decrease of its maximum absorbance, (ii) a blue shift of the maximum wavelength of both the light and the dark adapted forms. However (iii) a normal light adaptation is maintained and (iv) the retinal-retinal interactions are not perturbed. The role of valinomycin as a K(+)-carrier allowing a H(+)-K(+) competition as well as the stabilization of the deprotonated Schiff-base (linking retinal to the apo-opsin) is shown and discussed.

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Further Characterization of Anesthetic‐treated Purple Membranes

Cited by 16 publications

References 14 publications

Effect of a light-induced pH gradient on purple-to-blue and purple-to-red transitions of bacteriorhodopsin

Effect of a light-induced pH gradient on purple-to-blue and purple-to-red transitions of bacteriorhodopsin

Reversible inhibition of proton release activity and the anesthetic-induced acid-base equilibrium between the 480 and 570 nm forms of bacteriorhodopsin

Light adaptation of bacteriorhodopsin in the presence of valinomycin and potassium. pH-dependence

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