Infrared spectroscopy of phytochrome and model pigments

Siebert, Friedrich; Grimm, Rudolf; Rüdiger, Wolfhart; Schmidt, Gabriele; Scheer, Hugo

doi:10.1111/j.1432-1033.1990.tb19487.x

Cited by 41 publications

(53 citation statements)

References 45 publications

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“…The disagreement existing in the literature about the protonation state of Pf, (Fodor et al, 1990;Siebert et al, 1990;Mizutaniet al, 1991;Hildebrandt et al, 1992) is thus solved: The UV-resonant 1591-cm-I mode (component IV), which is not sensitive to deuteration (Mizutani et al, 1991) and does involve a vCN coordinate (this work), most likely from ring C, constitutes a good indicator for an unprotonated ring C in both the Pf, and P, forms. The visible-or near-IR-resonant 1595-cm-I mode (component V), which is sensitive to deuteriation (Fodor et al, 1990;Hildebrandt et al, 1992) and involves a C N stretch at ring D and a methine CC stretch at C15 (this work), is an indicator of the anti conformation at CIS but cannot constitute an indicator of protonation at ring C.…”

Section: Resultsmentioning

confidence: 96%

Structure and interactions of phycocyanobilin chromophores in phycocyanin and allophycocyanin from an analysis of their resonance Raman spectra

Szalontai¹,

Gombos²,

Csizmadia³

et al. 1994

Biochemistry

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Raman spectra of phycocyanobilin, phycocyanin, and allophycocyanin were obtained at resonance with their visible and near-UV transitions. These spectra were empirically assigned with the help of 14N- and 15N-isotopic substitutions and comparisons with resonance Raman spectra of phycoerythrin. These results confirm the previously suggested assignment of a conformation-sensitive band around 1239-1246 cm-1 to a mode involving nu CmH and nu CN coordinates. Computer-assisted decomposition of the complex, conformation-sensitive 1580-1670-cm-1 region yielded five components that we labeled I-V. The previously described spectral changes observed upon monomerization and denaturation in resonance Raman spectra of phycocyanin and allophycocyanin essentially arise from changes in the relative intensities of these components. Component I (around 1649-1651 cm-1) and component III (1621-1624 cm-1) originate predominantly from nu C=C at C15 of the chromophore. Their relative intensity ratio reflects the relative amounts of C15-Z-anti and C15-Z-syn methine bridge conformations, respectively. Component II (1633-1638 cm-1) is ascribed to a nu C=C mode of pyrrole rings; it is not sensitive to the chromophore conformation. Component IV is also conformation-insensitive and originates from nu C=N and nu C=C coordinates, most likely from ring C. Component V (1591-1594 cm-1) involves a nu C=N coordinate in ring D, coupled to a nu C=C coordinate of the C15 methine bridge. The implications of the present assignments on those of resonance Raman active modes of phytochrome are discussed. A consistent set of correlations between chromophore conformations and resonance Raman data is obtained for both phycobiliproteins and phytochrome.

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Section: Resultsmentioning

confidence: 96%

Structure and interactions of phycocyanobilin chromophores in phycocyanin and allophycocyanin from an analysis of their resonance Raman spectra

Szalontai¹,

Gombos²,

Csizmadia³

et al. 1994

Biochemistry

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“…Since the assignment of bands in vibrational spectra is still at an early stage, only a few aspects are discussed. The observed spectral homologies to the spectra of phyA (15,16) suggest that the chromophore structure of the parent states must be very similar in both pigments, whereas at low temperatures considerable spectral deviations are observed during the phototransformations which are probably due to the altered protein environment of the chromophore in Cph1.…”

Section: Introductionmentioning

confidence: 92%

“…From recent investigations of Cph1 by optical and FT-Raman spectroscopy it is assumed that the chromophore of Cph1 is protonated in Pr since considerable similarities to phyA were observed (12). In addition, from investigations on tetrapyrrole model compounds it is known that the absorbance frequency of the C 19 ϭO stretching vibration of the outer ring coupled with the conjugatedelectron system is found around 1690 cm Ϫ1 which is shifted to ഠ1705 cm Ϫ1 upon protonation of the pigment (15,21). Taking together these arguments we suggest that the Z,E isomerization of the protonated chromophore takes place during the formation of the first intermediate of the Pr → Pfr pathway.…”

Section: Ft-ir Spectroscopymentioning

confidence: 99%

The Photoreactions of Recombinant Phytochrome from the Cyanobacterium Synechocystis: A Low-Temperature UV–Vis and FT-IR Spectroscopic Study

Foerstendorf

Lamparter

Hughes

et al. 2000

Photochem Photobiol

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The interconvertible photoreactions of recombinant phytochrome from Synechocystis reconstituted with phycocyanobilin were investigated by light-induced optical and Fourier-transform infrared (FT-IR) difference spectroscopy at low temperatures for the first time. The photochemistry was found to be deferred below -100 degrees C for the transformation of red-absorbing form of phytochrome (Pr)-->far-red-absorbing form of phytochrome (Pfr), and no formation of an intermediate similar to the photoproduct of phytochrome A obtained at -140 degrees C (lumi-R) was observed. Two intermediates could be stabilized below -40 degrees C and between -40 and -20 degrees C, and were denoted as meta-Ra and meta-Rc, respectively. Above -20 degrees C Pfr was obtained. In the reverse reaction two intermediates could be stabilized below -60 degrees C (lumi-F) and between -60 and -40 degrees C (meta-F). The FT-IR difference spectra of the late Pr-->Pfr photoreaction show great similarities to the spectra obtained from oat phytochrome A suggesting similar conformation of the chromophore and interactions with its protein environment, whereas deviations in the spectra of meta-Ra were observed. A large band around 1700 cm-1 in the difference spectra between the intermediates and Pr which is tentatively assigned to the C19=O group of the prosthetic group indicates the Z,E isomerization around the C15=C16-methine bridge of the chromophore during the formation of meta-Ra. In the difference spectra of the parent states only small differences are observed in this region suggesting that the frequency of the carbonyl group is similar in Pr and Pfr. Since the FT-IR difference spectra between lumi-F and Pfr show great similarities to the spectra of the parent states, it is assumed that during the formation of lumi-F the chromophore largely returns into the primary Pr conformation. The FT-IR spectra recorded in a medium of 2H2O generally show a downshift of the significant bands due to the isotope effect. The appearance of a characteristic band around 935 cm-1 in all 2H2O spectra suggests an assignment to an N-2H bending vibration of the chromophore.

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“…It can at least be concluded from these results that a proton transfer from the chromophore to the protein is not closely linked to rate-limiting processes of dark relaxation steps. The assumption of a protonated chromophore not only in the Pr form, but also in the Pfr form as deduced from FT-IR spectra (Siebert et al, 1990), would support such a view of lack of a proton transfer during the photoconversion. This interpretation has, however, been questioned (Tokutomi et al, 1990;Mizutani et al, 1991).…”

Section: Chromophore Isomerization and Proton Transfermentioning

confidence: 84%

Events in the Phytochrome Molecule After Irradiation

Rüdiger¹

1992

Photochem & Photobiology

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Abstract-The photoconversion of Pr to Pfr has been investigated by a large number of investigators. We have previously demonstrated that Z,E isomerization of the tetrapyrrole chromophore is involved in the photoconversion. It is the best candidate for the primary photoreaction. Conformation and configuration of the Pr chromophore will be compared with that of chromophores in phycocyanin. The crystal structure of phycocyanin had been elucidated by x-ray analysis. Proton transfer and/or Z, E isomerization of the tetrapyrrole are probably involved in different steps of the photoconversion in phytochrome and in photoreversible phycobiliproteins. Fluorescence decay kinetics of irradiated Pr and intermediate formation show heterogeneity. Possible reasons for this heterogeneity will be discussed. Pisum sativum L.

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Infrared spectroscopy of phytochrome and model pigments

Cited by 41 publications

References 45 publications

Structure and interactions of phycocyanobilin chromophores in phycocyanin and allophycocyanin from an analysis of their resonance Raman spectra

Structure and interactions of phycocyanobilin chromophores in phycocyanin and allophycocyanin from an analysis of their resonance Raman spectra

The Photoreactions of Recombinant Phytochrome from the Cyanobacterium Synechocystis: A Low-Temperature UV–Vis and FT-IR Spectroscopic Study

Events in the Phytochrome Molecule After Irradiation

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