EXCITED STATE BEHAVIOR OF PHYTOCHROME P<sub>r</sub>

Teuchner, Klaus; Schulz, Michael; Stiel, H.; Maisch, Manfred; Rüdiger, Wolfhart

doi:10.1111/j.1751-1097.1995.tb02411.x

Cited by 6 publications

(3 citation statements)

References 21 publications

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“…A and 2 A). However, an ultrafast excited state relaxation with an estimated lifetime of ;100 fs, close to what we have found, was suggested by Teuchner et al (18) based on picosecond intensity-dependent transmission measurements.…”

supporting

confidence: 91%

“…Later studies confirmed this excited-state equilibration model in the P Ã r state (12,(17)(18)(19). However, the insight gained from fluorescence studies alone is limited, due to the high complexity of the excited-state dynamics of the very flexible chromophore.…”

Section: Introductionmentioning

confidence: 81%

“…However, the insight gained from fluorescence studies alone is limited, due to the high complexity of the excited-state dynamics of the very flexible chromophore. Consequently, additional ultrafast studies have been performed on native phys using ultrafast transient absorption techniques, in particular to characterize also the excited-state dynamics of P fr which could not be studied using fluorescence techniques due to its much faster, subpicosecond lifetime (17)(18)(19)(20)(21)(22)(23). Phytochrome from cyanobacteria as well as recombinant phys with modified chromophores have been also been studied by femtosecond spectroscopy (12).…”

Section: Introductionmentioning

confidence: 99%

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Femtosecond Kinetics of Photoconversion of the Higher Plant Photoreceptor Phytochrome Carrying Native and Modified Chromophores

Müller

Lindner

Martin

et al. 2008

Biophysical Journal

120

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The photoprocesses of native (phyA of oat), and of C-terminally truncated recombinant phytochromes, assembled instead of the native phytochromobilin with phycocyanobilin (PCB-65 kDa-phy) and iso-phycocyanobilin (iso-PCB-65 kDa-phy) chromophores, have been studied by femtosecond transient absorption spectroscopy in both their red absorbing phytochrome (P(r)) and far-red absorbing phytochrome (P(fr)) forms. Native P(r) phytochrome shows an excitation wavelength dependence of the kinetics with three main picosecond components. The formation kinetics of the first ground-state intermediate I(700), absorbing at approximately 690 nm, is mainly described by 28 ps or 40 ps components in native and PCB phytochrome, respectively, whereas additional approximately 15 and 50 ps components describe conformational dynamics and equilibria among different local minima on the excited-state hypersurface. No significant amount of I(700) formation can be observed on our timescale for iso-PCB phytochrome. We suggest that iso-PCB-65 kDa-phy either interacts with the protein differently leading to a more twisted and/or less protonated configuration, or undergoes P(r) to P(fr) isomerization primarily via a different configurational pathway, largely circumventing I(700) as an intermediate. The isomerization process is accompanied by strong coherent oscillations due to wavepacket motion on the excited-state surface for both phytochrome forms. The femto- to (sub-)nanosecond kinetics of the P(fr) forms is again quite similar for the native and the PCB phytochromes. After an ultrafast excited-state relaxation within approximately 150 fs, the chromophores return to the first ground-state intermediate in 400-800 fs followed by two additional ground-state intermediates which are formed with 2-3 ps and approximately 400 ps lifetimes. We call the first ground-state intermediate in native phytochrome I(fr 750), due to its pronounced absorption at that wavelength. The other intermediates are termed I(fr 675) and pseudo-P(r). The absorption spectrum of the latter already closely resembles the absorption of the P(r) chromophore. PCB-65 kDa-phy shows a very similar kinetics, although many of the detailed spectral features in the transients seen in native phy are blurred, presumably due to wider inhomogeneous distribution of the chromophore conformation. Iso-PCB-65 kDa-phy shows similar features to the PCB-65 kDa-phy, with some additional blue-shift of the transient spectra of approximately 10 nm. The sub-200 fs component is, however, absent, and the picosecond lifetimes are somewhat longer than in 124 kDa phytochrome or in PCB-65 kDa-phy. We interpret the data within the framework of two- and three-dimensional potential energy surface diagrams for the photoisomerization processes and the ground-state intermediates involved in the two photoconversions.

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supporting

confidence: 91%

Section: Introductionmentioning

confidence: 81%

Section: Introductionmentioning

confidence: 99%

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Femtosecond Kinetics of Photoconversion of the Higher Plant Photoreceptor Phytochrome Carrying Native and Modified Chromophores

Müller

Lindner

Martin

et al. 2008

Biophysical Journal

120

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Femtosecond time-resolved spectroscopy of the primary photochemistry of phytochrome

et al. 1997

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Time‐resolved absorption spectra of Pr phytochrome were obtained using a regeneratively amplified femtosecond titanium : sapphire laser system. The early time transient absorption spectra are comprised of prompt Pr photobleaching, stimulated emission, and excited‐state absorption features that decay with a 24 ps time constant that matches the ground state appearance time of the primary photoproduct. Based on the 5 ns radiative lifetime calculated from the absorption and spontaneous emission spectra and the fluorescence quantum yield of 5.5 (± 0.5) × 10−3, we calculate an excited‐state lifetime of 28 ps that agrees well with the directly determined lifetime. The transient absorption spectra are consistent with a primary photochemical reaction quantum yield of 0.15, and the absorption spectrum of the primary photoproduct closely resembles that of the low‐temperature trapped intermediate, lumi‐R. We conclude that the primary photoisomerization, which is believed to be a Z,syn → E,syn isomerization of the C15=C16 chromophore bond, occurs in 24 ps. © 1997 John Wiley & Sons, Inc. Biospectroscopy 3: 421–433, 1997

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Deprotonated 2,3‐Dihydrobilindiones—Models for the Chromophore of the Far‐Red‐Absorbing Form of Phytochrome

Stanek

Grubmayr

1998

Chemistry A European J

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Chromophore anions of synthetic 2,3-dihydrobilindiones can serve as models for the chromophore of the far-red-absorbing form of phytochrome because of the strong resemblance of their UV/Vis spectra. Significant red shifts of their long-wavelength maxima result from the elongation of the chromophores by deprotonation and the donor ± acceptor reversal upon the conversion of the ring A lactam (N 3CO) into the lactim anion (NC 2 O À ). The best resemblance was observed in the case of a 15-E configured chromophore anion. 13C NMR spectroscopic investigations demonstrated that changes in chromophore structure are caused not only by regioselective deprotonation of the 2,3-dihydrolactam moiety of ring A, but also by the subsequent dipyrrin tautomerization within rings B and C. Generally, the chromophore structure can be interpreted in terms of an oxygen-donor/oxygen-acceptor-substituted polyene. The remarkable red shift of the long wavelength maximum results from the strong donor power of the oxygen atom on ring A, where the negative charge is localized. A simple model can be proposed for the interconversion of the structurally different chromophores of the red-absorbing form (Pr) and the far-red-absorbing form (Pfr) of phytochrome, based on oppositely charged chromophore ions of different geometry and stability: a stable 15Z-configured cation for physiologically inactive Pr and a labile 15E-configured anion for physiologically active Pfr. Interconversion requires only two types of reactions, namely Z/E photoisomerization and proton transfer.

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EXCITED STATE BEHAVIOR OF PHYTOCHROME P_r

Cited by 6 publications

References 21 publications

Femtosecond Kinetics of Photoconversion of the Higher Plant Photoreceptor Phytochrome Carrying Native and Modified Chromophores

Femtosecond Kinetics of Photoconversion of the Higher Plant Photoreceptor Phytochrome Carrying Native and Modified Chromophores

Femtosecond time-resolved spectroscopy of the primary photochemistry of phytochrome

Deprotonated 2,3‐Dihydrobilindiones—Models for the Chromophore of the Far‐Red‐Absorbing Form of Phytochrome

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EXCITED STATE BEHAVIOR OF PHYTOCHROME Pr

Cited by 6 publications

References 21 publications

Femtosecond Kinetics of Photoconversion of the Higher Plant Photoreceptor Phytochrome Carrying Native and Modified Chromophores

Femtosecond Kinetics of Photoconversion of the Higher Plant Photoreceptor Phytochrome Carrying Native and Modified Chromophores

Femtosecond time-resolved spectroscopy of the primary photochemistry of phytochrome

Deprotonated 2,3‐Dihydrobilindiones—Models for the Chromophore of the Far‐Red‐Absorbing Form of Phytochrome

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EXCITED STATE BEHAVIOR OF PHYTOCHROME P_r