Intermolecular Interactions in Visual Pigments. The Hydrogen Bond in Vislon

Favrot, J.; Leclercq, J.; Roberge, R.; Sándorfy, C.; Vocelle, D.

doi:10.1111/j.1751-1097.1979.tb09267.x

Cited by 62 publications

(39 citation statements)

References 55 publications

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“…It is, therefore, a process which is typical for the transition from the stable species rhodopsin or isorhodopsin to their first photoproduct, bathorhodopsin. The modification of carboxylic groups may play a role in point-charge models of the chromophore in rhodopsin [6,32].…”

Section: Discussionmentioning

confidence: 99%

Fourier‐transform infrared spectroscopy applied to rhodopsin

Siebert

Mäntele

Gerwert

1983

European Journal of Biochemistry

110

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By measuring the rhodopsin -bathorhodopsin, isorhodopsin -bathorhodopsin, rhodopsin -isorhodopsin and rhodopsin --eta-I1 difference spectra with the method of Fourier-transform infrared spectroscopy we have identified the C=N stretching vibration of the protonated retinylidene Schiff base of rhodopsin, isorhodopsin and bathorhodopsin. In contrast to resonance Raman spectroscopy additional strong bands were observed between 1700cm-'and 1620cni-'. Most ofthemdependon theisomericstateofthechromophore. Theoriginofthese bands will be discussed. In the fingerprint region isorhodopsin and bathorhodopsin are quite similar but no similarities with infrared spectra of model compounds of any isomeric composition are observed. Therefore, no conclusions on the isomeric state of the retinal in bathorhodopsin can be drawn. We provide evidence for the modification of one or two carboxylic group(s) during the rhodopsin -bathorhodopsin and isorhodopsin -bathorhodopsin transition.During the last years evidence has accumulated to show that the main role of rhodopsin in the visual transduction process consists in its function as an activator of enzymatic reactions, switched on by the action of light (e.g. [I]). The molecular events leading to the activation of rhodopsin are still not well enough understood. A prerequisite for the understanding of this mechanism is the knowledge of the molecular events in the chromophore 1 I-cis retinal and in the protein, as well as the knowledge of the chromophore-protein interaction, especially of the nature of the chromophore-protein bond. Resonance Raman spectroscopy has provided evidence that the retinal-protein link constitutes a protonated Schiff base [2-51. This finding has been questioned on the basis of theoretical and experimental arguments [6 -121. To explain the discrepancy processes in the electronic excited state involved in resonance Raman spectroscopy have been proposed. With the method of time-resolved infrared spectroscopy we have previously measured the rhodopsin -meta-I and rhodopsin --eta-11 difference spectra [12]. In these measurements it was not possible to identify clearly the Cz=N stretching vibration of the protonated retinylidene Schiff base in rhodopsin, and a protonation via a hydrogen bond has, therefore, been suggested. These investigations were hampered by low spectral resolution (5 cm-' -8 cm-'). In addition, protein changes, which cause spectral changes, have been invoked to explain these observations. Nevertheless, since infrared difference spectroscopy does not involve the electronic excited state, it still would be desirable to apply this method at a higher spectral resolution to solve the problem of the nature of the retinal-protein link in rhodopsin. Recently, Fourier-transform infrared (FTIR) difference spectroscopy has been successfully employed to measure the static difference spectra in the systems of CO-myoglobin and bacteriorhoAhhrez;iutions. FTTR spectroscopy, Fourier-transform infrared spectroscopy; BR568r light-adapted form of bacteriorhodopsin; Kslo...

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Section: Discussionmentioning

confidence: 99%

Fourier‐transform infrared spectroscopy applied to rhodopsin

Siebert

Mäntele

Gerwert

1983

European Journal of Biochemistry

110

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“…The fact that there must be a counter-ion at the Schiff base nitrogen has been recognized by Schaffer (124,125). If the equilibrium is 100% in favor of the C=Ni-H form one can say that the Schiff base is entirely protonated.…”

Section: Protonationmentioning

confidence: 99%

“…125. It is readily demonstrated that if the counter-ion was an aliphatic anline it would take the proton from the Schiff base; if it contains another C=N, like pyridine or the imidazole ring of histidine, for example.…”

Section: Protonation and Hydrogen Bondingmentioning

confidence: 99%

“…Other theoretical results giving strength to Kropf and Hubbard's suggestion came from Abrahamson and Wiesenfeld (121) and Mantione and Pullman (12 I), Honig et al ( 1 23), and Favrot et ul. (124,125). Nakanishi, Honig, and their co-workers (102-110) have greatly developed the external point charge theory.…”

Section: The Saga O F the Resonance Raman Assault On Rh And Br Startementioning

confidence: 99%

“…Favrot et al (125,192) took isobutylidene-isopropylamine, (CH3)2CHCH=NCH(CH3)2, a simple non-conjugated Schiff base as their model. This aldimine is stable due to the branched substituents on both the carbon and the nitrogen of the double bond (Thiollais (193)).…”

Section: Protonation and Hydrogen Bondingmentioning

confidence: 99%

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The photochemical event in rhodopsins

Sándorfy¹,

Vocelle²

1986

Can. J. Chem.

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. 64, 225 1 (1986).The photochemical step in the functioning of visual and bacterial rhodopsins entails cis-trans or trans-cis isomerization and changes in the state of protonation of the retinylidene Schiff base chromophore. In this review our present knowledge on these two events is discussed as well as the role of interactions between the chromophore and the surrounding protein, opsin. The relation between protonation and hydrogen bonding at the Schiff base nitrogen, the problems of stabilization of the proton bridge and charge separation are also discussed. A new proposal is made which implies Schiff base to counter-ion proton translocation with concomitant isomerization and reprotonation of the chromophore.

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The Photochemistry of Rhodopsins

Ottolenghi

1980

Advances in Photochemistry

160

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Intermolecular Interactions in Visual Pigments. The Hydrogen Bond in Vislon

Cited by 62 publications

References 55 publications

Fourier‐transform infrared spectroscopy applied to rhodopsin

Fourier‐transform infrared spectroscopy applied to rhodopsin

The photochemical event in rhodopsins

The Photochemistry of Rhodopsins

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