Open AccessTrapping and charge stabilization in chlorosome containing bacteria: Comparative study on Chloroflexus aurantiacus and Chlorobium limicola
Author(s) -
Schmidt Kristiane,
Trissl HansWilhelm
Publication year - 1996
Publication title -
berichte der bunsengesellschaft für physikalische chemie
Language(s) - English
Resource type - Journals
ISSN - 0005-9021
DOI - 10.1002/bbpc.19961001205
Subject(s) - chlorosome , green sulfur bacteria , photochemistry , photosynthetic reaction centre , chemistry , fluorescence , trapping , bacteriochlorophyll , physics , pigment , electron transfer , biology , optics , organic chemistry , ecology
Trapping and charge stabilization in intact cells of Chloroflexus aurantiacus and Chlorobium limicola were studied by means of photovoltage kinetics and fluorescence emission spectra upon excitation in the chlorosome. 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 Chlorobium there were also two electrogenic phases of 105 ps and 650 ps. The later 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 proves the existence of at least two intermediary acceptors between the primary donor (P 840) and F x in the Chlorobium reaction center. In both species the photovoltage signal in the low excitation limit appeared after a lag phase of 55 to 65 ps, which is ascribed to the energy transfer from the chlorosome to the core pigments.