Abstract
Isolated chromatophore membranes and purified reaction centre light-harvesting B875 complex from the purple bacterium Rhodocyclus gelatinosus have been studied by EPR spectroscopy. Four haems occurring in approximately equal stoichiometries could be distinguished in chromatophores. The position of their g z peaks, their orientations with respect to the membrane and their electrochemical properties have been characterized ( g z = 3.40, E m = 320 ± 30mV, 0°: g z = 3.40, E m = 70 ± 20mV, 0: g z = 3.30, E m = 130 ± 20mV, 90°; g z = 3.15, E m = 300 ± 20mV, 90°). At ambient potentials where only the high potential haems are reduced (> + 200mV), the stable photooxidation of the + 300 mV haem occurred in a fraction (40%) of centres. Chemical prereduction of the + 130 mV haem allows stable charge separation at 4 K in all of the centres. In the case where all four haems are reduced prior to illumination, a subsequent stable photooxidation (at 4 K) of another haem seems to occur, resulting in trapping of the reduced states of both the primary quinone acceptor Q A and bacteriopheophytin.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callMore From: Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
