ISSN:
1573-5079
Keywords:
t Chlorobium
;
iron-sulfur centres
;
reaction centre complex
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract The EPR spectroscopic and electrochemical properties of FeS centres in membrane fragments and in isolated reaction centres from green sulfur bacteria purified as published previously (Hager-Braun C, Xie D-L, Jarosch U, Herold E, Büttner M, Zimmermann R, Deutzmann R, Hauska G and Nelson N (1995) Biochemistry 34: 9617–9624) were compared for the species t Chlorobium limicola and t Chlorobium tepidum. In addition, membrane samples from a third green sulfur bacterium, t Chlorobium vibrioforme were studied. The intactness of the isolated reaction centres was assayed from the amount of photoreducible FeS centres and spin-polarized triplet signal as compared to the parent membranes. The results obtained allow us to rationalize conflicting data published for the green sulfur bacterial reaction centres during recent years. The previously reported broad linewidths of the FeS centres in purified reaction centres were shown to be very likely due to detergent induced alterations. For the terminal FeS acceptors in purified reaction centres, a (preparation dependent) shift towards less negative redox midpoint potentials with respect to what is seen in the membranes was found. These redox midpoint potentials in intact membrane samples were seen to be significantly more negative than those of the respective FeS centres in Photosystem I from cyanobacteria and chloroplasts. The results demonstrate the high similarity concerning the characteristics of the terminal FeS acceptors in different green sulfur bacterial species.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1005787209977
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