TY - JOUR
T1 - Ultrafast pump-probe spectroscopy of the P700- and Fx-containing Photosystem I core protein from Synechococcus sp. PCC 6301 (Anacystis nidulans)
AU - Lin, Su
AU - van Amerongen, Herbert
AU - Struve, Walter S.
PY - 1992/11/16
Y1 - 1992/11/16
N2 - Time-resolved absorption difference profiles were obtained using one-color and two-color pump-probe techniques on the P700-containing core protein from the blue-green bacterium Synechococcus sp. PCC 6301, which contains approx. 100 chlorophyll (Chl) a antenna pigments per reaction center. Excitation wavelengths in the two-color studies were 665 and 680 nm; probe wavelengths ranged from 650 to 676 nm. The isotropic absorption difference spectra show evidence for rapid equilibration among Chl a spectral forms in the core antenna. In addition, they exhibit a dynamic blue shift with lifetime ∼ 9-14 ps, which occurs irrespective of excitation wavelength. Analyses of isotropic profiles for different combinations of pump and probe wavelengths yield four families of lifetime components: < 5 ps, which is attributed to spectral equilibration; 9-14 ps; several tens of ps (observed at wavelengths longer than 665 nm); and at least several hundred ps (observed at probe wavelengths 650 and 657 nm under 665 nm excitation). Anisotropic decays observed with identical pump and probe wavelengths exhibit large-amplitude components with easily resolved lifetimes (∼ 15 ps and ∼ 7 ps at 665 and 670 nm, respectively). The initial anisotropies are < 0.4, indicating that much faster depolarization processes also occur in these one-color experiments. The two-color anisotropy functions tend to be dominated by unresolvably fast decay, suggesting that mainstream energy transfer steps in the core antenna occur on a subpicosecond time scale.
AB - Time-resolved absorption difference profiles were obtained using one-color and two-color pump-probe techniques on the P700-containing core protein from the blue-green bacterium Synechococcus sp. PCC 6301, which contains approx. 100 chlorophyll (Chl) a antenna pigments per reaction center. Excitation wavelengths in the two-color studies were 665 and 680 nm; probe wavelengths ranged from 650 to 676 nm. The isotropic absorption difference spectra show evidence for rapid equilibration among Chl a spectral forms in the core antenna. In addition, they exhibit a dynamic blue shift with lifetime ∼ 9-14 ps, which occurs irrespective of excitation wavelength. Analyses of isotropic profiles for different combinations of pump and probe wavelengths yield four families of lifetime components: < 5 ps, which is attributed to spectral equilibration; 9-14 ps; several tens of ps (observed at wavelengths longer than 665 nm); and at least several hundred ps (observed at probe wavelengths 650 and 657 nm under 665 nm excitation). Anisotropic decays observed with identical pump and probe wavelengths exhibit large-amplitude components with easily resolved lifetimes (∼ 15 ps and ∼ 7 ps at 665 and 670 nm, respectively). The initial anisotropies are < 0.4, indicating that much faster depolarization processes also occur in these one-color experiments. The two-color anisotropy functions tend to be dominated by unresolvably fast decay, suggesting that mainstream energy transfer steps in the core antenna occur on a subpicosecond time scale.
KW - (Synechococcus)
KW - Antenna
KW - Chlorophyll a
KW - Cyanobacterium
KW - Photosystem I
KW - Pump-probe spectroscopy
KW - Ultrafast spectroscopy
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U2 - 10.1016/0005-2728(92)90013-R
DO - 10.1016/0005-2728(92)90013-R
M3 - Article
AN - SCOPUS:0026484969
VL - 1140
SP - 6
EP - 14
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
SN - 0005-2728
IS - 1
ER -