Premium
ELECTRON PARAMAGNETIC RESONANCE SIGNAL II IN SPINACH CHLOROPLASTS—I. HIGH RESOLUTION SPECTRA AND MORPHOLOGICAL LOCATION
Author(s) -
Esser Alfred F.
Publication year - 1974
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.1751-1097.1974.tb06563.x
Subject(s) - photosystem ii , spinach , chloroplast , electron paramagnetic resonance , p700 , chemistry , photosystem i , laser linewidth , signal (programming language) , thylakoid , nuclear magnetic resonance , photosynthetic reaction centre , light harvesting complexes of green plants , dcmu , analytical chemistry (journal) , photosynthesis , photochemistry , electron transfer , physics , optics , biochemistry , chromatography , laser , computer science , gene , programming language
—The electron paramagnetic resonance Signal II of spinach chloroplasts was recorded under high‐resolution conditions. The signal is asymmetric, has five lines of unequal intensity and splitting, a derivative linewidth of 20.0 G, and a g ‐value of 2.0051. The latter value varies between 2.0045 and 2.0052 since other signals contribute to the center portion of the spectrum. Signal II is present in dark‐adapted leaves and chloroplasts at a concentration of 50 per cent of the maximum light signal. It is not exhibited by stroma lamellae but is seen in grana thylakoid fractions. The maximum concentration of the material providing Signal II is found in a fraction (40 K) which has a very low Photosystem II activity. The unknown substance giving rise to Signal II may not be required for either Photosystem I or Photosystem II activity. Evidence presented here indicates that Signal II probably is not due to a free, mobile plastosemiquinone or a free, mobile plastochromanoxyl radical.