Circular Dichroism Spectra of Axially Oriented Rhodospirillum rubrum Cells and Their Fragments Immobilized in Polymer Film

Cegielski, R.; Fra̧ckowiak, D.; Liang, Jim

doi:10.12693/aphyspola.79.479

Cited by 4 publications

(4 citation statements)

References 11 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This shows once more that the structure of PE occurring in various organisms can be different. Previously measured CD spectra of PBS and their fragments (37, 38) do not exhibit CD changes, which could suggest an exciton splitting. Therefore, FRET mechanism should instead be responsible for observed ET.…”

Section: Resultsmentioning

confidence: 85%

“…Absorptions of various PE chromophores are highly overlapped, and in the PE obtained from various organisms different contents of PUB chromophores were found (1, 33–36). Circular dichroism (CD) spectroscopy (10,11, 37) as well as polarized light fluorescence(12) can be helpful in the analysis of such complex spectra. The investigations of cryptomonad PE (10) show the occurrence of several types of PE, which are marked according to their absorption spectra, for example, as PE 545 for one type of PE, which was investigated in detail by McColl et al (1999) (12).…”

Section: Resultsmentioning

confidence: 99%

“…The measurement of CD spectra, which might provide information about exciton splitting between chromophores, is not easy to interpret for whole PBS or their fragments (37) because various pigment spectra are highly overlapped and the scattering of circularly polarized light on large complexes is very strong. In partially denaturated PBS (38) it is possible to separate CD signals for various biliproteins.…”

Section: Resultsmentioning

confidence: 99%

See 2 more Smart Citations

Fluorescence Polarization Studies of B‐Phycoerythrin Oriented in Polymer Film¶

Fra̧ckowiak

Ptak

Gryczyński

et al. 2004

Photochem & Photobiology

View full text Add to dashboard Cite

Polarized steady-state fluorescence and fluorescence excitation spectra as well as time-resolved fluorescence for B-phycoerythrin (B-PE) from red algae, Porphyridium cruentum, embedded in polyvinyl stretched films were measured. The lifetimes of polarized fluorescence were analyzed using exponential components and fractal models. The interactions between various chromophores of the pigment-protein complexes investigated were discussed. The anisotropy of fluorescence excitation spectra differs from the anisotropy of absorption spectra and depends on the wavelength of observation. This shows that differently oriented chromophores take part in various paths of excitation energy transfer (ET) or change their excitation into heat with various efficiencies (or both). Also, analysis of time-resolved fluorescence measured in various spectral regions gives different polarized components of emission. Fractal analysis of lifetimes, done under supposition of the Foerster resonance ET mechanism, suggests different arrangements of energy donors and acceptors for molecules absorbing in different spectral regions. It shows that several fractions of differently oriented "forms" of chromophores exhibiting different spectral properties occur in B-PE complexes. Small changes in the orientation of the chromophores can be followed by modification of the path of excitation energy migration. Based on the results obtained a new reorientational mechanism of the State 1 --> State 2 transition was proposed: Even small conformational modifications of biliproteins, which could be caused in vivo by the change in the conditions of preillumination of bacteria, are able to modify the path of excitation ET. Such a reorientation may be responsible for the change in the partition of biliprotein excitation energy between photosystem II (PSII) and PSI (State 1 --> State 2 transition). The proposed mechanism needs further verification by the investigation of whole bacteria cells.

show abstract

Section: Resultsmentioning

confidence: 85%

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Fluorescence Polarization Studies of B‐Phycoerythrin Oriented in Polymer Film¶

Fra̧ckowiak

Ptak

Gryczyński

et al. 2004

Photochem & Photobiology

View full text Add to dashboard Cite

show abstract

“…Different photosynthetic samples, much more complex than pigment solutions, were investigated in our laboratory: complexes separated from the organisms (Frąckowiak et al 1982, parts of the photosynthetic apparatus of plants or bacteria ) and small photosynthetic organisms (Cegielski et al 1991. We have applied several spectral methods to follow all paths of deactivation of the absorbed energy (Fig.…”

Section: Samples and Methodsmentioning

confidence: 99%