Anion-induced wavelength regulation of absorption maxima of Schiff bases of retinal

Blatz, Paul E.; Mohler, Jonathan H.; Navangul, Himanshoo V.

doi:10.1021/bi00755a026

Cited by 211 publications

(148 citation statements)

References 17 publications

(22 reference statements)

Supporting

Mentioning

138

Contrasting

Unclassified

Order By: Relevance

“…Again, the external point charges were shown to be contributors to the spectroscopic characteristics of the model system. Other factors were shown to be important also: the distance between the minimum nitrogen and the counteranion (an effect already described by Blatz and co-workers (5)) and solvent polarity.…”

Section: Introductionmentioning

confidence: 59%

Effects of solvents on a model of rhodopsin consisting of a conjugated imine and substituted acetic acids

Bissonnette¹,

Thanh²,

Vocelle³

1984

Can. J. Chem.

View full text Add to dashboard Cite

A model system of rhodopsin consisting of a dienylidene Schiff base and different halogeno acids has been studied in two solvents, chloroform and methanol, by uv and 400-MHz nmr spectroscopies. The uv results indicate that in chloroform, a nonpolar solvent, monohalogenoacetic acids can protonate the Schiff base only partially, while nmr data show that the aldimine hydrogen is slightly affected by acids and that the acidic proton is moving rapidly between the donor and the acceptor. In methanol, data indicate a leveling effect. In relation with rhodopsin, our results imply that, depending on the environment surrounding the chromophore, the state of protonation of the Schiff base could be strongly affected. Finally. our model shows experimental evidence that Nakanishi's external point charge could be operating in visual pigments.MARTINE BISSONNETTE, HOA LE THANH et DANIEL VOCELLE. Can. J. Chem. 62, 1459 (1984). Un modkle de la rhodopsine comprenant une base de Schiff diknylidkne et differents acides halogCnCs a CtC CtudiC dans le chloroforme et le mCthanol par les spectroscopies ultraviolette et rCsonance magnCtique nuclCaire (400 MHz). Les rCsultats dans l'uv indiquent que dans un solvant non polaire comme le chloroforme, les acides acCtiques monohalogCnCs peuvent protoner la base de Schiff que partiellement tandis que la rmn montre que l'hydrogene de I'aldimine n'est que peu affect6 par la presence d'acides et que le proton acide se dtplace rapidement entre le donneur et I'accepteur. Dans le mCthanol, les donntes indiquent la prtsence d'un effet tqualisateur dii au solvant. Extrapolis h la rhodopsine, nos rtsultats impliquent que I'ttat de protonation du chromophore peut &tre affect6 grandement par le milieu environnant la base de Schiff. Finalcment, notre modkle prCsente quelques donnCes expCrimentales tendant h montrer I'existence d'une charge externe prks du chromophore telle que prtconiste par Nakanishi.

show abstract

Section: Introductionmentioning

confidence: 59%

Effects of solvents on a model of rhodopsin consisting of a conjugated imine and substituted acetic acids

Bissonnette¹,

Thanh²,

Vocelle³

1984

Can. J. Chem.

View full text Add to dashboard Cite

show abstract

“…In the dark state of rhodopsin it is largely accepted that increasing the counterion-PSB distance red shifts, while decreasing the distance blue shifts, the absorption maximum (25)(26)(27)(28)(29)(30). In batho, the newly introduced twist in the chromophore complicates calculation of the counterion-PSB distance.…”

Section: Scheme IIImentioning

confidence: 99%

Chromophore structural changes in rhodopsin from nanoseconds to microseconds following pigment photolysis

Jäger

Lewis

Zvyaga

et al. 1997

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

View full text Add to dashboard Cite

Rhodopsin is a prototypical G proteincoupled receptor that is activated by photoisomerization of its 11-cis-retinal chromophore. Mutant forms of rhodopsin were prepared in which the carboxylic acid counterion was moved relative to the positively charged chromophore Schiff base. Nanosecond time-resolved laser photolysis measurements of wild-type recombinant rhodopsin and two mutant pigments then were used to determine reaction schemes and spectra of their early photolysis intermediates. These results, together with linear dichroism data, yielded detailed structural information concerning chromophore movements during the first microsecond after photolysis. These chromophore structural changes provide a basis for understanding the relative movement of rhodopsin's transmembrane helices 3 and 6 required for activation of rhodopsin. Thus, early structural changes following isomerization of retinal are linked to the activation of this G protein-coupled receptor. Such rapid structural changes lie at the heart of the pharmacologically important signal transduction mechanisms in a large variety of receptors, which use extrinsic activators, but are impossible to study in receptors using diffusible agonist ligands.Rhodopsin is the light-triggered membrane receptor in rod outer segments responsible for dim-light vision. Absorption of light transforms rhodopsin (rho) into an activated state, which interacts with a heterotrimeric G protein to initiate an enzyme cascade leading to visual transduction. To reach this active state, called metarhodopsin (meta) II (1, 2), rho passes through a number of intermediates that have been characterized by UV-visible, Fourier-transform infrared (FTIR), Raman, and NMR spectroscopies, in addition to spin-labeling and biochemical studies (3-10). One way to characterize the intermediates is to trap them at low temperatures. This approach led to the classical ''bleaching'' scheme ( max values in nanometers): rho (498) 3 bathorhodopsin (batho) (542) 3 lumirhodopsin (lumi) (497) 3 meta I (480) 3 meta II (380) Scheme I However, at more physiologically relevant temperatures, time-resolved measurements up to 1 msec after photolysis reveal a new intermediate and a different kinetic scheme (3, 11). The following reaction scheme was proposed to occur during the nanosecond-to-microsecond time regime (3): rho (498) 3 batho (529) ª bsi (477) 3 lumi (492) 3 . . . Scheme II The new intermediate, blue-shifted intermediate of rho (bsi), is entropically favored and thus not trapped at low temperatures (11).The role of various structural features of the retinal chromophore in early rho photointermediates has been studied through time-resolved spectral measurements of artificial rho, in which the native chromophore is replaced by synthetically modified retinals (12). In studies of bacteriorhodopsin, timeresolved absorption spectroscopy has been shown to be particularly valuable when combined with site-directed mutagenesis to probe the roles of specific protein residues in different intermediates (13). Unti...

show abstract

“…Much attention has been given to seeking an understanding of the origin of the absorption spectra of these two pigments. A simple retinylidene Schiff base absorbs at 370 nm while its protonated counterpart exhibits a red-shifted absorption band at 440 nm (methanol) (4). In comparison, the natural pigments have absorption maxima at 506 nm for bovine rhodopsin and 570 nrn for bacteriorhodopsin (5,6).…”

Section: Introductionmentioning

confidence: 99%

“…Cation-anion interactions have bee* suggested to be an important determinant in wavelength regulation. Blatz et al showed that there was a linear relationship between the reciprocal of the square of the anion radius and the energy difference between the ground and the first excited states of a retinylidene salt (4). This correlation was then used to calculate the position of the absorption maximum as a function of the internuclear distance between the protonated Schiff base nitrogen atom and the counterion.…”

Section: Introductionmentioning

confidence: 99%

Structure and wavelength modification in retinylidene iminium salts

Elia¹,

Childs²,

Britten³

et al. 1996

Can. J. Chem.

View full text Add to dashboard Cite

Abstract:The spectroscopic and structural properties of the perchlorate and triflate salts of N-n-butyl-retinylidene imine, 2 and 3, have been examined in solution and solid phases. In solution these salts were found to exhibit very similar UV and NMR spectroscopic properties. However, in the solid state marked differences in their absorption spectra (2, A, , = 504 nm; 3, A, , , = 445 nm) and I3c NMR spectra were found. The structures of the two salts were determined by X-ray crystallography. The cations in each of the salts were shown to have very similar conformations, detailed structures, and packing in their crystal lattices. The differences in the spectroscopic properties of the salts in the solid state could not be accounted for on the basis of any structural differences in the cations themselves. In terms of cation-anion interactions, a strong hydrogen bonding interaction was found in each case between the N-H proton and an oxygen atom of the counterion. However, there were significant differences between the two salts in terms of the N-H..O internuclear distances (2, N-H...O = 2.939(7) A and in 3,2.85(1) A). The results are strongly suggestive that the wavelength and positive charge delocalization in retinylidene iminium salts are controlled by variation of the distance between the anion and the proton bonded to the Schiff base nitrogen atom. The work reported here represents the first examples of secondary retinylidene iminium salts containing an N-alkyl substituent to be successfully analyzed by X-ray crystallography. The relationship of these observations in the solid state to the spectroscopic properties of the natural visual pigments is explored.Key words: retinylidene iminium salts, iminium salts, cation-anion interactions. Resum6: On a Ctudie les propriCtCs spectroscopiques et structurales des perchlorate et triflate de la N-n-butyl-ritinylidene imine, 2 et 3, tant en solution qu'en phase solide. En solution, on a trouvC que ces sels prCsentent des propriCtCs spectroscopiques UV et RMN qui sont tres semblables. Toutefois, ii I'ttat solide, on a observe des difftrences marqutes dans leurs spectres d'absorption (2, A, , , = 504 nm; 3, A, , , = 445 nm) et dans leurs spectres RMN du I3c. On a determint les structures des deux sels par diffraction des rayons X. Dans chacun de ces sels, les cations ont des conformations, des structures dCtaillCes et des empilements trks semblables. On ne peut pas expliquer les differences observCes dans les propri6tCs spectroscopiques des sels ii l'etat solide sur la base de differences de structures dans les cations eux-mtmes. En termes d'interactions cation-anion, on a observe une forte interaction de liaison hydrogene entre le proton N-H et l'atome d'oxygkne du contre-ion. Toutefois, il existe des differences importantes entre les deux sels en termes de distances internuclCaires (2, N-H...O = 2,939(7) A et dans 3,2,85(1) A. Les rksultats suggerent fortement que la longueur d'onde et la dClocalisation de la charge positive dans les sels rktinylidkne iminium est contr6...

show abstract

Anion-induced wavelength regulation of absorption maxima of Schiff bases of retinal

Cited by 211 publications

References 17 publications

Effects of solvents on a model of rhodopsin consisting of a conjugated imine and substituted acetic acids

Effects of solvents on a model of rhodopsin consisting of a conjugated imine and substituted acetic acids

Chromophore structural changes in rhodopsin from nanoseconds to microseconds following pigment photolysis

Structure and wavelength modification in retinylidene iminium salts

Contact Info

Product

Resources

About