Premium
FLASH PHOTOLYSIS‐ELECTRON SPIN RESONANCE: A KINETIC STUDY OF ENDOGENOUS LIGHT‐INDUCED FREE RADICALS IN REACTION CENTER PREPARATIONS FROM RHODOPSEUDOMONAS SPHEROIDES *
Author(s) -
Bolton James R.,
Cost Konstantine
Publication year - 1973
Publication title -
photochemistry and photobiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.818
H-Index - 131
eISSN - 1751-1097
pISSN - 0031-8655
DOI - 10.1111/j.1751-1097.1973.tb06442.x
Subject(s) - flash photolysis , photochemistry , chemistry , electron paramagnetic resonance , electron acceptor , radical , photosynthetic reaction centre , photodissociation , signal (programming language) , resonance (particle physics) , kinetic energy , kinetics , electron transfer , nuclear magnetic resonance , reaction rate constant , biochemistry , atomic physics , physics , quantum mechanics , computer science , programming language
— Using the technique of flash photolysis‐electron spin resonance, we have detected, by means of a kinetic analysis, a rapidly decaying signal in reaction center preparations from the R26 blue‐green mutant of Rhodopseudomonas spheroides. This signal, which we designate Signal B3, is essentially the same as that seen previously in iron‐free preparations. Signal B3 decays at 20°C with a 1/ e time of ˜ 3 ms and exhibits an activation energy of 5 ± 1 kcal mol ‐1 over the temperature range 0–30°C. Extraction with isooctane completely eliminates Signal B3, whereas readdition of exogenous ubiquinone‐30 completely restores the signal. o ‐Phenanthroline has no effect on Signal B3. We discuss these results in terms of a model in which the primary acceptor is an iron‐ubiquinone complex with excess ubiquinone serving as a secondary electron acceptor pool.