Delayed fluorescence from bacteriochlorophyll in Chromatium vinosum chromatophores: characteristics in the presence of o-phenanthroline.
Delayed fluorescence from bacteriochlorophyll in the chromatophores of Chromatium vinosum, a photosynthetic purple sulfur bacterium, was studied in the presence of o-phenanthroline (o-phen) under intermittent illumination. Re-reduction of the photooxidized reaction center bacteriochlorophyll (P+) in the dark interval was accelerated by o-phen. This effect was attributed to the return of electrons trapped in the primary electron acceptor (A) to P+. In the presence of o-phen, the time course of the decay of delayed fluorescence was not coincident with that of the re-reduction of P+. The delayed fluorescence was somewhat intensified at the early stage (within 30 ms) of relaxation in the dark period. Prolonged illumination (longer than 20 ms) or uncouplers such as carbonylcyanide m-chlorophenylhydrazone (CCCP) or valinomycin plus nigericin decreased the intensity of delayed fluorescence and suppressed the stimulation of delayed fluorescence at the early stage. Delayed fluorescence from reaction center-rich subchromatophore particles decayed with a time course identical to that of the reduction of P+ and was not affected by CCCP, in the presence of o-phen. The intensification at the early stage in the chromatophores can be interpreted in terms of charge separation between pairs of P and A, primary electron donor and acceptor molecules, oriented perpendicular to the intact chromatophore membrane, the effect decreasing in parallel with the recombination of P+ and A-.
D020130:Bacterial Chromatophores; D001429:Bacteriochlorophylls / Q000378:metabolism* / Q000528:radiation effects; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone / Q000494:pharmacology; D002734:Chlorophyll / Q000031:analogs & derivatives*; D002844:Chromatium; D008027:Light; D009550:Nigericin / Q000494:pharmacology; D010084:Oxidation-Reduction; D010618:Phenanthrolines / Q000494:pharmacology*; D010777:Photochemistry; D013050:Spectrometry, Fluorescence; D014634:Valinomycin / Q000494:pharmacology
D001429:Bacteriochlorophylls; D010618:Phenanthrolines; D002734:Chlorophyll; D014634:Valinomycin; D002258:Carbonyl Cyanide m-Chlorophenyl Hydrazone; D009550:Nigericin