Excitation Energy Transfer Between Sensitizing Chromophores of Phycocyanin 612

Csatorday, K.; MacColl, Robert; Guard-Friar, Deborah; Hanzlik, Cheryl A.

doi:10.1111/j.1751-1097.1987.tb07893.x

Cited by 16 publications

(8 citation statements)

References 8 publications

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“…These findings for PC645 were significantly different than the ones that have been proposed for phycocyanin 612, where the main pathway for energy migration was suggested to be from one sensitizing chromophore to another. [49][50][51] Similarly as found in a number of biliproteins, the decay of the lowest-energy fluorescing chromophore was measured to be between 1.6 and 2.1 ns.…”

Section: Introductionsupporting

confidence: 67%

Ultrafast light harvesting dynamics in the cryptophyte phycocyanin 645

Mirkovic

Doust

Kim

et al. 2007

Photochem Photobiol Sci

133

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Steady-state and femtosecond time-resolved optical methods have been used to study spectroscopic features and energy transfer dynamics in the soluble antenna protein phycocyanin 645 (PC645), isolated from a unicellular cryptophyte Chroomonas CCMP270. Absorption, emission and polarization measurements as well as one-colour pump-probe traces are reported in combination with complementary quantum chemical calculations of electronic transitions of the bilins. Estimation of bilin spectral positions and energy transfer rates aids in the development of a model for light harvesting by PC645. At higher photon energies light is absorbed by the centrally located dimer (DBV, beta50/beta61) and the excitation is subsequently funneled through a complex interference of pathways to four peripheral pigments (MBV alpha19, PCB beta158). Those chromophores transfer the excitation energy to the red-most bilins (PCB beta82). We suggest that the final resonance energy transfer step occurs between the PCB 82 bilins on a timescale estimated to be approximately 15 ps. Such a rapid final energy transfer step cannot be rationalized by calculations that combine experimental parameters and quantum chemical calculations, which predict the energy transfer time to be 40 ps.

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Section: Introductionsupporting

confidence: 67%

Ultrafast light harvesting dynamics in the cryptophyte phycocyanin 645

Mirkovic

Doust

Kim

et al. 2007

Photochem Photobiol Sci

133

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“…Another important contribution comes from the more isolated chromophores. For phycocyanin 612, these maxima are at 551 and 576 nm (Csatorday et al, 1987), and for phycocyanin 645, they are at 557.5 and 624 nm . Both proteins were analyzed by the same deconvolution method ( Table 2).…”

Section: Resultsmentioning

confidence: 95%

Picosecond Fluorescence From Phycocyanin 612

Malak¹,

MacColl²

1991

Photochem & Photobiology

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Abgtract--The biliprotein, phycocyanin 612, was purified from a cryptomonad, Hemiselmis virescem.The protein, which is an a2& dimer having four spectrally different tetrapyrrole chromophores, was studied using picosecond fluorescence by exciting the various chromophores at three wavelengths, 565, 585 and 615 nm. These wavelengths were chosen to excite selectively the three highest energy chromophores. Decay times were meapred as the excitation energy migrated from each of the three excited chromophores to the lowest-energy chromophore. The ps decay times were found to be 9, 13, and 12 ps for excitations at 565, 585, and 615 nm, respectively. A comparison is made between phycocyanin 612 and phycocyanin 645 with regard to the causes of their differing absorption maxima..

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“…These three biliproteins are all α 2 β 2 oligomeric proteins having eight bilins. Previous studies with phycocyanin 612 did not consider the possibility of a pair of bilins across the monomer−monomer interface ( , ). The best evidence for the intermonomer pair of bilins is a difference CD spectrum of monomers subtracted from dimers.…”

Section: Resultsmentioning

confidence: 99%

Bilin Organization in Cryptomonad Biliproteins

et al. 1999

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The bilin organization of three cryptomonad biliproteins (phycocyanins 612 and 645 and phycoerythrin 545) was examined in detail. Two others (phycocyanin 630 and phycoerythrin 566) were studied less extensively. Phycocyanin 645 and phycoerythrin 545 were suggested to have one bilin in each monomeric (alphabeta) unit of the dimer (alpha2beta2) isolated from the others, and the remaining six bilins may be in pairs. One pair was found across the monomer-monomer interface of the protein dimer, and two identical pairs were proposed to be within the monomer protein units. For phycocyanin 612, a major surprise was that a pair of bilins was apparently not found across the monomer-monomer interface, but the remaining bilins were distributed as in the other two cryptomonad proteins. The effect of temperature on the CD spectra of phycocyainin 612 demonstrated that two of the bands (one positive and one negative) behaved identically, which is required if they are coupled. The two lowest-energy CD bands of phycocyanin 612 originated from paired bilins, and the two higher-energy bands were from more isolated bilins. The paired bilins within the protein monomers contained the lowest-energy transition for these biliproteins. Using the bilins as naturally occurring reporter groups, phycocyanin 612 was shown to undergo a reversible change in tertiary structure at 40 degrees C. Protein monomers were shown to be functioning biliproteins. A hypothesis is that the coupled pair of bilins within the monomeric units offers important advantages for efficient energy migration, and other bilins transfer energy to this pair, extending the wavelength range or efficiency of light absorption.

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Excitation Energy Transfer Between Sensitizing Chromophores of Phycocyanin 612

Cited by 16 publications

References 8 publications

Ultrafast light harvesting dynamics in the cryptophyte phycocyanin 645

Ultrafast light harvesting dynamics in the cryptophyte phycocyanin 645

Picosecond Fluorescence From Phycocyanin 612

Bilin Organization in Cryptomonad Biliproteins

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