Resonance Raman studies of the purple membrane

Aton, B.; Doukas, Apostolos G.; Callender, Robert; Becher, B.; Ebrey, Thomas G.

doi:10.1021/bi00632a029

Cited by 351 publications

(323 citation statements)

References 20 publications

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“…(12). M4,, is unique, as it is the only intermediate whose Schiff base is unprotonated, while the parent pigment and all the other intermediates are protonated (4,(13)(14)(15)(16)(17). Some studies have inferred that the Schiff base deprotonation is closely associated with the proton pump mechanism (18,19) and the effect of chemically modified tyrosines on the rate of decay of MqI2 suggests a coupling between some tyrosines and M4,, (20)(21)(22)(23)(24).…”

Section: Introductionmentioning

confidence: 99%

Effect of salt on the tyrosine and protonated Schiff base deprotonation kinetics in bacteriorhodopsin

Dupuis¹,

El‐Sayed²

1985

Can. J. Chem.

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It is observed that the number of protons pumped per M,,, formed in the bacteriorhodopsin photocycle almost doubles at high salt concentrations. In this paper, we studied the rates of deprotonation of tyrosine and of the two components of the protonated Schiff base at high salt concentrations, and at different pHs and temperatures. It is found that at pH = 7, increasing the salt concentration decreases the rates of deprotonation of the protonated Schiff base and tyrosine. 'This strongly suggests that the observed gain in the quantum yield of proton release per M412 formed when the salt concentration is increased is not a result of an increase in these rates. However, at high pH, e.g. 9.6, increasing the salt concentration increases the rate of deprotonation of the Schiff base by about 50%. Under all conditions, the slow component of the Schiff base is found to lose its proton prior to tyrosine. PAUL DUPUIS et M. A. EL-SAYED. Can. J. Chem. 63, 1699 (1985.A de fortes concentrations en sel, le nombre de protons pompes pour chaque Ma,? forme au cours du photocycle de la bacteriorhodopsine est pratiquement double. Dans cette publication,nous rapportons les resultats d'une etude, i des fortes concentrations en sel, a divers pH et i diverses temperatures, sur les vitesses de dkprotonation de la tyrosine et des deux composantes de la base de Schiff protonee. On a trouve qu'i un pH de 7 I'augmentation de la concentration en sel diminue les vitesses de deprotonation de la base de Schiff protonee et de la tyrosine. Ceci suggkre fortement que I'augmentation observee du rendement quantique des protons lib&& pour chaque M412 forme lorsqu'on augmente la concentration du sel n'est pas dG ? i une augmentation de ces vitesses. Cependant, si on op&re i un pH d'environ 9,6 et que I'on augmente la concentration du sel, on provoque aussi une augmentation de la vitesse de deprotonation de la base de Schiff de I'ordre de 50%. On a trouve que, quelles que soient les conditions, la composante lente de la base de Schiff perd son proton avant la tyrosine.[Traduit par le journal]

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Section: Introductionmentioning

confidence: 99%

Effect of salt on the tyrosine and protonated Schiff base deprotonation kinetics in bacteriorhodopsin

Dupuis¹,

El‐Sayed²

1985

Can. J. Chem.

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“…3, 4 and references therein). Although the electronic absorption of the retinylic chromophore in the ground state could be explained equally well by assuming covalent N' -H bonding or by a strong hydrogen bond between Ni6 and a proton donor belonging to the apoprotein (5), it was the interpretation of the resonance Raman spectra of rhodopsin that led to the prevalent opinion in favour of protonated N16 (6,7). However, the I3C nmr spectra of rhodopsin appeared to oppose this view (8) and also the results of differential kinetic infrared spectroscopy were interpreted in terms of the initially unprotonated N16 (9).…”

Section: Introductionmentioning

confidence: 99%

Ab-initio calculations on the retinal Schiff base – formic acid and allylimine – formic acid hydrogen bonds

Hodošček¹,

Hadži²

1985

Can. J. Chem.

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M~LAN HODOSCEK and DUSAN HADZI. Can. J. Chem. 63, 1528 (1985). The proton potential functions of Schiff base -formic acid complexes were calculated in the ab-initio scheme with STO-3G and 4-31G basis sets without and with the inclusion of a perturbing charge. The comparison of the curves with the retinal Schiff base and allylimine obtained by using the short base encouraged further calculations with the longer base on the truncated system only. The curve obtained with the 4-31G set on the allylimine -formic acid complex is of a double minimum type with the deeper well still at the formyl oxygen. Inclusion of a perturbing negative charge near the hydrogen bond reverses the depth of the wells making the N-protonated form more stable.MILAN HODOS~EK et DUSAN HADZI. Can. J. Chem. 63, 1528 (1985). Faisant appel i des schemas ab-itzitio et utilisant des bases STO-3G et 4-31G avec ou sans I'inclusion d'une charge perturbante, on a calcul6 les fonctions de potentiel des protons de complexes entre I'acide formique et des bases de Schiff.Une comparaison des courbes relatives a la base de Schiff du retinal et de I'allylamine, obtenues a I'aide de la base la plus courte, nous a encourage i proceder des calculs plus approfondis que nous avons effectues uniquement sur le systeme tronque en utilisant un base de calcul elargie. La courbe que nous avons obtenue pour le complexe de l'acide formique et de l'allylimine, en utilisant une base de calcul 4-31G, comporte un double minimum et le puit le plus profond est encore fix6 a l'oxygene. L'inclusion, pres de la liaison hydrogene, d'une charge perturbantc negative renverse la profondeur des puits et rend ainsi la forme N-protonke plus stable.[Traduit par le journal] Introduction In the series of hydrogen bonds involved in the light transduction mechanisms of both rhodopsin and bacteriorhodopsin (1, 2), the bond between the retinal Schiff base nitrogen (N,,) and a proton offering group in the opsin deserves particular attention. In explaining the bathochochromic shift that occurs upon bonding of retinal to the apoprotein it was necessary to invoke both a positive charge on N16 of the retinal Schiff base and a negative charge in the vicinity of C14 of retinal (refs. 3, 4 and references therein). Although the electronic absorption of the retinylic chromophore in the ground state could be explained equally well by assuming covalent N' -H bonding or by a strong hydrogen bond between Ni6 and a proton donor belonging to the apoprotein (5), it was the interpretation of the resonance Raman spectra of rhodopsin that led to the prevalent opinion in favour of protonated N16 (6, 7). However, the I3C nmr spectra of rhodopsin appeared to oppose this view (8) and also the results of differential kinetic infrared spectroscopy were interpreted in terms of the initially unprotonated N16 (9). Sandorfy and co-workers have elaborated a scheme (10-15) reconciling both extreme views, i.e. the protonated and unprotonated Schiff base. The essence of this scheme is a strong hydrogen bond with a double minim...

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“…0005-2728/84/$03.00 © 1984 Elsevier Science Publishers B.V. absorption properties are accompanied by specific proton movements and by configurational changes of the protonated Schiff's base, i.e., a reversible all-trans to 13-cis isomerization [4,5]. Limited information exists on the timing of isomerization.…”

Section: Introductionmentioning

confidence: 99%

Optical picosecond studies of bacteriorhodopsin containing a sterically fixed retinal

Polland

Franz

Kaiser

et al. 1984

Biochimica et Biophysica Acta (BBA) - Bioenergetics

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The photochemical behaviour of an analogous bacteriorhodopsin (9,12-Ph-BR) which contains the sterically fixed 9,12-phenylretinal has been investigated with picosecond spectroscopy. The following results have been obtained. No ground-state intermediate photoproduct is found in agreement with the previous observation that 9,12-Ph-BR does not exhibit proton pumping under illumination. The excited singlet state has a lifetime of ¢s-10 + 2 ps. This lifetime agrees favourably with the value calculated from the radiative lifetime ¢~d ----6.2 ns and the fluorescence quantmn efficiency of 1.2 • 10-3 Excited-state absorption occurs which results in fluorescence in the ultraviolet region. These various observations differ drastically from the corresponding findings on bacteriorhodopsin. Most important for an understanding of the differences is the fact that 9,12-phenylretinal does not isomerize in the protein's binding site in contrast to retinal. Our data therefore suggest that the formation of the intermediate K observed in bacteriorhodopsin is accompanied by the all-trans to 13-c/s isomerization.

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Resonance Raman studies of the purple membrane

Cited by 351 publications

References 20 publications

Effect of salt on the tyrosine and protonated Schiff base deprotonation kinetics in bacteriorhodopsin

Effect of salt on the tyrosine and protonated Schiff base deprotonation kinetics in bacteriorhodopsin

Ab-initio calculations on the retinal Schiff base – formic acid and allylimine – formic acid hydrogen bonds

Optical picosecond studies of bacteriorhodopsin containing a sterically fixed retinal

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