Bacteriorhodopsins with a chemically modified chromophore. The light‐driven proton pump action of [13‐demethyl‐11,14‐epoxy]‐, [9‐demethyl]‐, [13‐demethyl]‐ and [9,13‐bisdemethyl]‐bacteriorhodopsin

Muradin-Szweykowska, M.; Broek, A. D.; Lugtenburg, J.; Bend, R L van der; Dijck, P.W.M. Van

doi:10.1002/recl.19831020106

Cited by 13 publications

(6 citation statements)

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“…These effects in turn can alter the nature of the binding of the Schiff-base proton. For example, in BR in which the retinal has been replaced with the analog 13-demethyl-l1,1Cepoxyretinal (1 1,14-epoxy BR) (17). the addition of a furan ring to the polyene chain of the chromophore blocks isomerization of the retinal upon photoexcitation, so that no photoreactions are observed when this pigment is illuminated with nanosecond pulses of yellow light (18).…”

Section: Introductionmentioning

confidence: 99%

Electric‐Field Effects in 13‐Demethyl‐11,14‐Epoxyretinal‐Bacteriorhodopsin Films

Kolodner¹,

Лукашев

Ching³

et al. 1999

Photochem & Photobiology

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Abstract— We report the results of experiments on the application of electric fields across thin, dry Alms of a bacteriorho‐dopsin (BR) analog pigment in which the retinal chro‐mophore has been replaced with 13‐demethyl‐11,14‐epoxyretinal. As previously observed in other BR variants with low Schiff‐base pK values, this pigment exhibits protonation and deprotonation of the Schiff base under an applied electric field, depending on the initial Schiff‐base protonation state or effective pH. At low effective pH, a fast (<200 μs) deprotonation reaction dominates. At high pH, an apparently different mechanism leads to Schiff‐base protonation on the time scale of seconds. Comparison of our results with a simple model suggests that the external field causes a shift in the pK of the Schiff base by1–2 pH units.

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Section: Introductionmentioning

confidence: 99%

Electric‐Field Effects in 13‐Demethyl‐11,14‐Epoxyretinal‐Bacteriorhodopsin Films

Kolodner¹,

Лукашев

Ching³

et al. 1999

Photochem & Photobiology

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“…retinal does not bind to bO [Ltf* In continuation of our study on the effect of the different methy groups in retinal upon the binding properties and the light-driven proton pump action of bR [7], we now report on the binding properties of 5-demethyiretinai ( fig. 1) (in its dl-trans, 13-c&, 1 I-& and 9-c& form) to bO.…”

Section: Proton Pumpmentioning

confidence: 99%

“…The incorporation of bR (analogue) into phospholipid vesicles was performed and the lightdriven proton pump action was determined as in [7,10]. Nigericin was added to 2.5 ,ug/mg bR and valinomycin to 1 pg/mg bR.…”

Section: Incorporation Of Br (Analogue) Into Phospholipid Vesiclesmentioning

confidence: 99%

“…The denaturation experiments and HPLC analysis of the isolated isomers of 5-demethylretinal were performed as in [2,7].…”

Section: Light-dark Adaptation and Denaturation Experimentsmentioning

confidence: 99%

“…Bacteriorhodopsin (hereafter bR), the light energy converting protein of the purple membrane of the halo~hili~ microorganism Iiutobucreriwn halobium, occurs in a light-(Amax = 570 nm) and in a dark-adapted form (hmBX = 560 nm) [2]* The chromophore of the lightadapted form is an all-irons retinylidene moiety. In the dark-adapted form a 1: 1 ~~~ibrium between 13-t& and all-Pans isomers exists [Z].retinal does not bind to bO [Ltf* In continuation of our study on the effect of the different methy groups in retinal upon the binding properties and the light-driven proton pump action of bR [7], we now report on the binding properties of 5-demethyiretinai ( fig. 1) (in its dl-trans, 13-c&, 1 I-& and 9-c& form) to bO.…”

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(5‐demethyl)‐Bacteriorhodopsin analogue: its formation and light‐driven proton pump action

et al. 1983

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The binding of the isomers fall-trans, tfcis, f f-c& and 94s) of ~~~~~t~~lr~t~~~ to ~~~t~~i~o~~~~ and the light-dark adaptation as well as the tight-driven proton pump action of the resulting bacteriorhodopsin analogue were studied. The (Sdemethyl)-bacteriorhodopsin is formed -3-times faster than unmodified bacteriorhodopsin and shows an efficient light-driven proton pump action. These findings show that upon binding of retinal to bacterioopsin the protein forces the chromophore to adopt a more planar ring-chain conformation than in free retinal.~~obacterium hatobium &r@e mernb~~e Proton pumpChromoproteins with a retinylidene chromophore such as bacteriorhodapsin, visual pigments and retinochrome, play an important role in photobiology [I]. Bacteriorhodopsin (hereafter bR), the light energy converting protein of the purple membrane of the halo~hili~ microorganism Iiutobucreriwn halobium, occurs in a light-(Amax = 570 nm) and in a dark-adapted form (hmBX = 560 nm) [2]* The chromophore of the lightadapted form is an all-irons retinylidene moiety. In the dark-adapted form a 1: 1 ~~~ibrium between 13-t& and all-Pans isomers exists [Z].retinal does not bind to bO [Ltf* In continuation of our study on the effect of the different methy groups in retinal upon the binding properties and the light-driven proton pump action of bR [7], we now report on the binding properties of 5-demethyiretinai ( fig. 1) (in its dl-trans, 13-c&, 1 I-& and 9-c& form) to bO. The light-dark adaptation together with the light-driven proton pump action of (%demethyl)-bR are also discussed. 2, MATERIALS AND METHODS The

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Preparation of 11,14‐epoxy‐bridged and isomeric chain‐demethylated retinals. 13‐Demethyl‐11,14‐epoxy‐, 9‐demethyl‐, 13‐demethyl‐ and 9,13‐bisdemethyl‐retinals

Broek

Muradin-Szweykowska

Courtin

et al. 1983

Recl. Trav. Chim. Pays‐Bas

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1 p1 of 10 mM oxalic acid. To some samples, valinomycin was added in such a concentration (2 pI of the 0.1 mg/ml solution) that the steady state value of the proton transport was i n c r e a~e d '~. To each sample, nigericin was added in such an amount ( I pI of the 0.1 mg/ml solution) that the AjiH of the membrane was destroyed 14. l 4 K . HellinywerS, Ph. D. Thesis, Amsterdam (1979).Preparation of 11,14-epoxy-bridged and isomeric chain-demethylated retinals. 13-Demethyl-ll,14-epoxy-, 9-demethyl-, 13-demethyl-and 9,13-bisdemethyl-retinals Abstract. 9-Cis-and all-trans-l3-demethyl-l I , 14-epoxyretinyl acetate were prepared via a Wittig coupling between P-ionylidenetriphenylphosphonium bromide (1) and 5-(acetoxymethyl)furfural. Saponification of these acetates, subsequent oxidation and HPLC separation afforded pure 9-cisand all-trans-] 3-demethyl-1 1,lCepoxyretinal. 1 1-Cis-and all-trans-9-demethyl-, 13-demethyl-and 9,13-bisdemethyl-retinaI were prepared via the same scheme, based on the Pommer vitamin A acetate synthesis. Their photochemistry shows the same type of solvent dependence as retinal. HPLC separation of the photostationary mixtures of these retinals yielded the all-trans, 13-, I I-, 9-and 7-cb isomers in 98% purity. IntroductionIn the preceding paper' we described the preparation of modified bacteriorhodopsins by the reaction of 13-demethyl-] 1,14-epoxyretinal and geometric isomers of 9--demethyl-, 13-demethyl-and 9,13-bisdemethylretinals with bacterioopsin. Investigations into the possible light--driven proton pump action and light/dark adaptation of these pigment analogues led to new information concerning the conformation of the chromophore and the process of proton pumping. In this paper, the syntheses of the required retinals are described. A simple method, based on the Wittig reaction, is given for the preparation of all-trans-and 9-cis-13--demethyl-1 1,14-epoxyretinal. For the synthesis of all--trans-and 1 l-cis-9-demethyl, 13-demethyl-and 9,13-bisdemethylretinal, we applied the Wittig reaction. The isomers were separated by preparative HPLC. Irradiation of the all-trans isomer of the demethylated retinals in a suitable solvent gives rise to photostationary mixtures of 7-, 9-, 11-and 13-cis isomers from which preparative amounts with over 98 % chemical purity could be isolated by HPLC. SynthesisFor the preparation of 9-cis-13-demethyl-l l ,14-epoxyretinal (5) and all-trans-13-demethyl-l l, 14-epoxyretinal (6) we used the approach depicted in Scheme 1. The synthesis of the Wittig salt 1, starting from j3-ionone, has been previously described*. 5-(Acetoxymethyl)furfural (2) is commercially available. The Wittig coupling between 1 and 2, using butyllithium as base, gives a I : I mixture of the bridged retinyl acetates 3 and 4. Saponification of 3 and 4 and subsequent oxidation with MnO, affords a I : 1 mixture of the 11,14-epoxy-bridged retinal 5 and 6 (overall yield 78 %). Both retinals could be separated by HPLC into pure 5 and 6. They were characterized by 'H N M R spectroscopy, NOE difference ...

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Bacteriorhodopsins with a chemically modified chromophore. The light‐driven proton pump action of [13‐demethyl‐11,14‐epoxy]‐, [9‐demethyl]‐, [13‐demethyl]‐ and [9,13‐bisdemethyl]‐bacteriorhodopsin

Cited by 13 publications

References 13 publications

Electric‐Field Effects in 13‐Demethyl‐11,14‐Epoxyretinal‐Bacteriorhodopsin Films

Electric‐Field Effects in 13‐Demethyl‐11,14‐Epoxyretinal‐Bacteriorhodopsin Films

(5‐demethyl)‐Bacteriorhodopsin analogue: its formation and light‐driven proton pump action

Preparation of 11,14‐epoxy‐bridged and isomeric chain‐demethylated retinals. 13‐Demethyl‐11,14‐epoxy‐, 9‐demethyl‐, 13‐demethyl‐ and 9,13‐bisdemethyl‐retinals

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