Advanced

Studies on energy dissipation in phycobilisomes using the Kennard-Stepanov relation between absoption and fluorescence emission spectra

Björn, Lars Olof LU and Björn, G S (1986) In Photochemistry and Photobiology 44(4). p.535-542
Abstract
Absorption and fluorescence emission spectra were measured at room temperature (ca. 22.degree.C) for solutions of phycocyanin-1, phycocyanin-2, and allophycocyanin from Phormidium luridum, and also for phycobilisome preparations from various blue-green algae (Anabaena variabilis, Nostoc muscorum strain A, Nostoc sp. strain Mac. Phormidium luridum). Kennard-Stepanov (KS) temperatures (T) were computed using the Kennard-Stepanov relationship F(.lambda.) = b A (.lambda.) (.lambda.-5 exp(-hc/.lambda.kT), where F(.lambda.) stands for fluorescence (energy per wavelength interval) as a function of wavelength (.lambda.), A(.lambda.) is absorbance as a function of wavelength, b a proportionality factor, and h, c and k are Planck's constant, the... (More)
Absorption and fluorescence emission spectra were measured at room temperature (ca. 22.degree.C) for solutions of phycocyanin-1, phycocyanin-2, and allophycocyanin from Phormidium luridum, and also for phycobilisome preparations from various blue-green algae (Anabaena variabilis, Nostoc muscorum strain A, Nostoc sp. strain Mac. Phormidium luridum). Kennard-Stepanov (KS) temperatures (T) were computed using the Kennard-Stepanov relationship F(.lambda.) = b A (.lambda.) (.lambda.-5 exp(-hc/.lambda.kT), where F(.lambda.) stands for fluorescence (energy per wavelength interval) as a function of wavelength (.lambda.), A(.lambda.) is absorbance as a function of wavelength, b a proportionality factor, and h, c and k are Planck's constant, the velocity of light and Boltzmann's constant, respectively. In most cases experimental data followed the expected relationship, but at low ionic strength allophycocyanin gave a clearly biphasic KS plot, i.e. In .lambda.5 F(.lambda.)/A(.lambda.) vs l /.lambda.. This could be due to the presence of both monomers and trimers in the sample at low ionic strength. For purified allophycocyanin and phycocyanins (PC-1 and PC-2) as well as phycobilisomes from Phormidium luridum, the KS temperatures were only slightly (insignificantly) elevated above the sample temperature. Thus, after absorption of a photon, vibrational and configurational equilibration is essentially completed before emission of the fluorescence photon takes place. For phycobilisomes from Anabaena variabilis and the two Nostoc species the KS temperatures were moderately elevated. Since there was no correlation between radiation temperature and excitation wavelength, the elevation is not due to excess (undissipated) vibrational energy, but rather to incomplete configurational equilibration. (Less)
Please use this url to cite or link to this publication:
author
organization
publishing date
type
Contribution to journal
publication status
published
subject
in
Photochemistry and Photobiology
volume
44
issue
4
pages
535 - 542
publisher
American Society for Photobiology
ISSN
0031-8655
language
English
LU publication?
yes
id
4300c8f2-5358-4ffd-af5d-938889887be0 (old id 134573)
date added to LUP
2007-07-30 13:31:16
date last changed
2016-04-15 19:53:55
@article{4300c8f2-5358-4ffd-af5d-938889887be0,
  abstract     = {Absorption and fluorescence emission spectra were measured at room temperature (ca. 22.degree.C) for solutions of phycocyanin-1, phycocyanin-2, and allophycocyanin from Phormidium luridum, and also for phycobilisome preparations from various blue-green algae (Anabaena variabilis, Nostoc muscorum strain A, Nostoc sp. strain Mac. Phormidium luridum). Kennard-Stepanov (KS) temperatures (T) were computed using the Kennard-Stepanov relationship F(.lambda.) = b A (.lambda.) (.lambda.-5 exp(-hc/.lambda.kT), where F(.lambda.) stands for fluorescence (energy per wavelength interval) as a function of wavelength (.lambda.), A(.lambda.) is absorbance as a function of wavelength, b a proportionality factor, and h, c and k are Planck's constant, the velocity of light and Boltzmann's constant, respectively. In most cases experimental data followed the expected relationship, but at low ionic strength allophycocyanin gave a clearly biphasic KS plot, i.e. In .lambda.5 F(.lambda.)/A(.lambda.) vs l /.lambda.. This could be due to the presence of both monomers and trimers in the sample at low ionic strength. For purified allophycocyanin and phycocyanins (PC-1 and PC-2) as well as phycobilisomes from Phormidium luridum, the KS temperatures were only slightly (insignificantly) elevated above the sample temperature. Thus, after absorption of a photon, vibrational and configurational equilibration is essentially completed before emission of the fluorescence photon takes place. For phycobilisomes from Anabaena variabilis and the two Nostoc species the KS temperatures were moderately elevated. Since there was no correlation between radiation temperature and excitation wavelength, the elevation is not due to excess (undissipated) vibrational energy, but rather to incomplete configurational equilibration.},
  author       = {Björn, Lars Olof and Björn, G S},
  issn         = {0031-8655},
  language     = {eng},
  number       = {4},
  pages        = {535--542},
  publisher    = {American Society for Photobiology},
  series       = {Photochemistry and Photobiology},
  title        = {Studies on energy dissipation in phycobilisomes using the Kennard-Stepanov relation between absoption and fluorescence emission spectra},
  volume       = {44},
  year         = {1986},
}