K. Schmidt et Hw. Trissl, TRAPPING AND CHARGE STABILIZATION IN CHLOROSOME CONTAINING BACTERIA -COMPARATIVE-STUDY ON CHLOROFLEXUS-AURANTIACUS AND CHLOROBIUM-LIMICOLA, Berichte der Bunsengesellschaft fur Physikalische Chemie, 100(12), 1996, pp. 1958-1961
Citations number
17
Categorie Soggetti
Chemistry Physical
Journal title
Berichte der Bunsengesellschaft fur Physikalische Chemie
Trapping and charge stabilization in intact cells of Chloroflexus aura
ntiacus and Chlorobium limicola were studied by means of photovoltage
kinetics and fluorescence emission spectra upon excitation in the chlo
rosome. In Chloroflexus two electrogenic phases with time constants of
100 ps for trapping (P+ H- formation) from the core-complexes and 530
ps for charge stabilization (Q(A) reduction) were found. In Chlorobiu
m there were also two electrogenic phases of 105 ps and 650 ps. The la
ter phase most likely represents the charge stabilization on the iron-
sulfur center, F-X. A comparison of stationary fluorescence spectra of
both species indicates that the trapping time from the core pigments
in Chlorobium is significantly faster than in Chloroflexus. This prove
s the existence of at least two intermediary accepters between the pri
mary donor (P 840) and F-X in the Chlorobium reaction center. In both
species the photovoltage signal in the low excitation limit appeared a
fter a lag phase of 55 to 65 ps, which is ascribed to the energy trans
fer from the chlorosome to the core pigments.