Interconversion pathways of the protonated ?-ionone Schiff base: An ab initio molecular dynamics study

Terstegen, Frank; Carter, Emily A.; Buß, Volker

doi:10.1002/(sici)1097-461x(1999)75:3<141::aid-qua4>3.0.co;2-9

Cited by 12 publications

(3 citation statements)

References 39 publications

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“…7 We have simulated the photoreaction of rhodopsin on the basis of a five-double-bond model of the 11-cis retinal pSb chromophore using ab initio molecular dynamics (AIMD). 8 Our findings show that the distortion of the chromophore induced by steric interaction with the protein pocket is sufficient to make the photoreaction super fast, highly efficient, and stereoselective. The analysis of 18 trajectories reveals that the initial photochemical event which culminates in the isomerization of the cis double bond involves the three central bonds only, making this twisted region of the chromophore what might be called an inherently hot photochemical spot.…”

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confidence: 77%

“…Cembran et al have characterized the static evolution of 11- cis retinal in S 1 by calculating the minimal energy path (MEP) . We have simulated the photoreaction of rhodopsin on the basis of a five-double-bond model of the 11- cis retinal pSb chromophore using ab initio molecular dynamics (AIMD) . Our findings show that the distortion of the chromophore induced by steric interaction with the protein pocket is sufficient to make the photoreaction super fast, highly efficient, and stereoselective.…”

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confidence: 91%

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The Twisted C11C12 Bond of the Rhodopsin ChromophoreA Photochemical Hot Spot

Weingart

2007

J. Am. Chem. Soc.

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The photochemical cis−trans isomerization of a five double bond 11-cis retinal model has been investigated using ab initio molecular dynamics in vacuo and zero-point energy sampling. The trajectories show that the reaction in the excited-state is restricted to the C10−C13 fragment of retinal. The protein-induced torsion of the C11C12 and C12−C13 bonds are sufficient to maintain the stereoselectivity and the quantum efficiency of the retinal photoconversion in rhodopsin.

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confidence: 77%

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confidence: 91%

The Twisted C11C12 Bond of the Rhodopsin ChromophoreA Photochemical Hot Spot

Weingart

2007

J. Am. Chem. Soc.

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“…These assignments, in turn, indicate that there is an inversion in the ring conformation. Buss and coworkers70,71 have calculated that the energy barrier for ring inversion is between 5-6 kcal/mol. Moreover, these results show that in both rhodopsin and Meta II, the C16 and C17 chemical shifts are unique and that averaging by rotation of the ionone ring does not occur in the retinal binding site of the protein.…”

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confidence: 99%

6-s-cis Conformation and Polar Binding Pocket of the Retinal Chromophore in the Photoactivated State of Rhodopsin

et al. 2009

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The visual pigment rhodopsin is unique among the G protein-coupled receptors in having an 11-cis retinal chromophore covalently bound to the protein through a protonated Schiff base linkage. The chromophore locks the visual receptor in an inactive conformation through specific steric and electrostatic interactions. This efficient inverse agonist is rapidly converted to an agonist, the unprotonated Schiff base of all-trans retinal, upon light activation. Here, we use magic angle spinning NMR spectroscopy to obtain the 13 C chemical shifts (C5-C20) of the all-trans retinylidene chromophore and the 15 N chemical shift of the Schiff base nitrogen in the active metarhodopsin II intermediate. The retinal chemical shifts are sensitive to the conformation of the chromophore and its molecular interactions within the protein-binding site. Comparison of the retinal chemical shifts in metarhodopsin II with those of retinal model compounds reveals that the Schiff base environment is polar. In particular, the 13 C15 and 15 Nε chemical shifts indicate that the C=N bond is highly polarized in a manner that would facilitate Schiff base hydrolysis. We show that a strong perturbation of the retinal 13 C12 chemical shift observed in rhodopsin is reduced in wild-type metarhodopsin II and in the E181Q mutant of rhodopsin. On the basis of the T 1 relaxation time of the retinal 13 C18 methyl group and the conjugated retinal 13 C5 and 13 C8 chemical shifts, we have determined that the conformation of the retinal C6-C7 single bond connecting the β-ionone ring and the retinylidene chain is 6-s-cis in both the inactive and the active states of rhodopsin. These results are discussed within the general framework of ligand-activated G protein-coupled receptors.

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Schnelle Photoisomerisierung eines Rhodopsinmodells – eine Ab-initio-Moleküldynamikstudie

Buß¹,

Weingart²,

Sugihara³

2000

Angewandte Chemie

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Professor Paul von RagueÂ Schleyer zum 70. Geburtstag gewidmetDie protonierte Schiff-Base (PSB) von 11-cis-Retinal ist der Chromophor von Rhodopsin, dem Photorezeptor in der Retina des Wirbeltierauges (Schema 1). Die photochemische Isomerisierung in die all-trans-Form löst eine Serie von enzymatischen Reaktionen aus, die sogenannte Sehkaskade, die schlieûlich zur Erregung des Sehnervs führt. [1] Zentral für das Verständnis dieses Vorgangs auf molekularer Ebene ist die Geometrie des Retinalchromophors, die sich von der 11cis-12-s-trans-Konformation ableitet [2] und als Folge sterischer Wechselwirkungen verdrillt wirde. Hinweise hierfür kommen von der Resonanz-Raman- [3] sowie direkter von der Circulardichroismus(CD)-Spektroskopie: [4] Nach der Bindung durch das Protein weist das optisch inaktive 11-cis-Retinal deutliche positive CD-Banden auf, die mit den Absorptionsmaxima des Chromophors im UV/Vis-Bereich bei 500 und 340 nm korrelieren. Mit unterschiedlichen Festkörper-NMR-Methoden ist es gelungen, die Torsionswinkel des Chromophors [5] und die Abstände zwischen ausgewählten isotopenmarkierten Atompositionen zu bestimmen. [6] Daraus wurden Winkel von ca. 428 zwischen den Ebenen C7-C8-C9-C10 und C13-C14-C15 abgeleitet.Die sterische Wechselwirkung mit dem Protein und die daraus resultierende Verformung des Chromophors werden allgemein für die extreme Kinetik und Effizienz der Photoreaktion des Rhodopsins verantwortlich gemacht, die das erste Photoprodukt nach nur 200 fs liefert: [7] Die Entfernung der Methylgruppe an C13 führt nach spektroskopischen Befunden zu einer Einebnung des Chromophors; gleichzeitig geht die Quantenausbeute erheblich zurück: von 0.65 auf 0.47 oder sogar noch weniger. [8,9] Führt man die Methylgruppe an

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Interconversion pathways of the protonated ?-ionone Schiff base: An ab initio molecular dynamics study

Cited by 12 publications

References 39 publications

The Twisted C11C12 Bond of the Rhodopsin ChromophoreA Photochemical Hot Spot

The Twisted C11C12 Bond of the Rhodopsin ChromophoreA Photochemical Hot Spot

6-s-cis Conformation and Polar Binding Pocket of the Retinal Chromophore in the Photoactivated State of Rhodopsin

Schnelle Photoisomerisierung eines Rhodopsinmodells – eine Ab-initio-Moleküldynamikstudie

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