Volatile anesthetics cause conformational changes of bacteriorhodopsin in purple membrane

Nishimura, Shinya; Mashimo, Takashi; Hiraki, Kenji; Hamanaka, Toshiaki; Kito, Yuji; Yoshiya, Ikuto

doi:10.1016/0005-2736(85)90018-5

Cited by 35 publications

(20 citation statements)

References 24 publications

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“…The acid-induced difference spectra obtained ( Figure 4a) are very similar in profile to those reported for native purple membrane (Moore et al, 1978;Mowery et al, 1979;Kimura et al, 1984). When HhPL vesicles were alkalized (pH >9), on the other hand, an absorption decrease at 570 nm was accompanied by an absorption (Pande et al, 1989a;Nishimura et al, 1985).…”

Section: ( I ) Light-induced P H Changes In Reconstituted Vesiclessupporting

confidence: 65%

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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Section: ( I ) Light-induced P H Changes In Reconstituted Vesiclessupporting

confidence: 65%

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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“…As previously observed by other investigators (Nishimura et al, 1985), addition of volatile anesthetics induces drastic changes in the absorption properties of purple membranes. Figure 1 shows the time course of the change in the absorption spectrum of PM after the addition of enflurane.…”

Section: Resultssupporting

confidence: 79%

“…With respect to its absorption spectrum, the 480 nm form of purified bacteriorhodopsin much resembles the 480 nm pigment which is formed upon incorporation of dimethyl sulfoxide or volatile anesthetics (Nishimura et al, 1985) into purple membranes. In view of this fact, we have investigated the 480 nm pigment formed upon addition of volatile anesthetics to purple membranes by means of absorption or transient absorption spectroscopy.…”

Section: Introductionmentioning

confidence: 99%

Further Characterization of Anesthetic‐treated Purple Membranes

Henry

Beaudoin

Baribeau

et al. 1988

Photochem & Photobiology

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Abstract— The absorption maximum of bacteriorhodopsin is shifted from 568 nm to 480 nm when halogenated volatile anesthetics (enflurane; halothane) are added to purple membranes. Analysis of the rate of formation of this new species upon addition of the anesthetic and of the back‐formation of native bacteriorhodopsin upon its removal indicate that in purple membranes, the dark‐adapted chromophore is much less reactive than its light‐adapted counterpart. Lipid‐soluble molecules thus have a lower accessibility to the dark‐adapted chromophore. In addition, activity of the 480 nm bacteriorhodopsin was investigated. Flash and steady‐state photolysis experiments reveal that this blue shifted chromophore has full photochemical activity. It has a meta‐intermediate absorbing maximally at 380 nm. The photocycle ofBR–480 is mainly characterized by a slow decay of the “O” intermediate, enabling the direct observation of the branching reaction between the “M” intermediate and the parentBR–480 pigment.

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“…It exists as a highly ordered membrane structure with an extremely low PL/protein ratio that confers exceptional stability against thermal and chemical degradation (26). The PM explicates its bioactivity when exposed to light (1) or to other external stimuli, such as general anesthetics, that are capable to modify the bR local pK a values (27,28).…”

Section: Resultsmentioning

confidence: 99%

“…In the case of PLs, their interaction with anesthetic molecules has been studied since the discovery that anesthetics effectiveness correlates with their own lipophilicity (Meyer-Overton rule) (25). Hypotheses on the general anesthesia mechanism involving anesthetics interactions with PL membranes as well as with the protein hydrophobic regions have been formulated (35); among others, also PMs are known to be sensitive to anesthetics (28). The opportunity to study these key relevant interfacial interactions and possibly contribute to shed light on the general anesthesia action mechanism was the driving force to choose volatile general anesthetics as external stimuli for both the PL and PM FBI-OFETs.…”

Section: Resultsmentioning

confidence: 99%

Interfacial electronic effects in functional biolayers integrated into organic field-effect transistors

Angione

Cotrone

Magliulo

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

111

102

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Biosystems integration into an organic field-effect transistor (OFET) structure is achieved by spin coating phospholipid or protein layers between the gate dielectric and the organic semiconductor. An architecture directly interfacing supported biological layers to the OFET channel is proposed and, strikingly, both the electronic properties and the biointerlayer functionality are fully retained. The platform bench tests involved OFETs integrating phospholipids and bacteriorhodopsin exposed to 1-5% anesthetic doses that reveal drug-induced changes in the lipid membrane. This result challenges the current anesthetic action model relying on the so far provided evidence that doses much higher than clinically relevant ones (2.4%) do not alter lipid bilayers' structure significantly. Furthermore, a streptavidin embedding OFET shows label-free biotin electronic detection at 10 parts-per-trillion concentration level, reaching state-of-the-art fluorescent assay performances. These examples show how the proposed bioelectronic platform, besides resulting in extremely performing biosensors, can open insights into biologically relevant phenomena involving membrane weak interfacial modifications.organic electronics | analytical bioassay | electronic biodetection

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Volatile anesthetics cause conformational changes of bacteriorhodopsin in purple membrane

Cited by 35 publications

References 24 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

Further Characterization of Anesthetic‐treated Purple Membranes

Interfacial electronic effects in functional biolayers integrated into organic field-effect transistors

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