Autor: |
Novoderezhkin V; A. N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Moscow 119899, Russia., Fetisova Z |
Jazyk: |
angličtina |
Zdroj: |
Biophysical journal [Biophys J] 1999 Jul; Vol. 77 (1), pp. 424-30. |
DOI: |
10.1016/S0006-3495(99)76900-6 |
Abstrakt: |
A model of pigment organization in the B808-866 bacteriochlorophyll a antenna of the green photosynthetic bacterium Chloroflexus aurantiacus based on femtosecond pump-probe studies is proposed. The building block of the antenna was assumed to be structurally similar to that of the B800-850 light-harvesting 2 (LH2) antenna of purple bacteria and to have the form of two concentric rings of N strongly coupled BChl866 pigments and of N/2 weakly coupled BChl808 monomers, where N = 24 or 32. We have shown that the Qy transition dipoles of BChl808 and BChl866 molecules form the angles 43 degrees +/- 3 degrees and 8 degrees +/- 4 degrees, respectively, with the plane of the corresponding rings. Using the exciton model, we have obtained a quantitative fit of the pump-probe spectra of the B866 and B808 bands. The anomalously high bleaching value of the B866 band with respect to the B808 monomeric band provided the direct evidence for a high degree of exciton delocalization in the BChl866 ring antenna. The coherence length of the steady-state exciton wave packet corresponds to five or six BChl866 molecules at room temperature. |
Databáze: |
MEDLINE |
Externí odkaz: |
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