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PICOSECOND FLUORESCENCE STUDIES OF P700‐ENRICHED PARTICLES OF SPINACH CHLOROPLASTS
Author(s) -
Kamogawa Keui,
Morris John M.,
Takagi Yoshihiro,
Nakashima Nobuaki,
Yoshihara Keitaro,
Ikegami Isamu
Publication year - 1983
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.1751-1097.1983.tb04460.x
Subject(s) - p700 , picosecond , fluorescence , photochemistry , photosystem i , chemistry , light harvesting complexes of green plants , analytical chemistry (journal) , photosynthetic reaction centre , chlorophyll a , photosystem ii , excited state , nanosecond , spinach , photobleaching , photosynthesis , atomic physics , laser , optics , electron transfer , physics , chromatography , biochemistry
Dynamic properties of the picosecond fluorescence of highly enriched reaction‐center particles of photosystem I (8 ‐ 10 chlorophylls/P700) prepared from spinach have been investigated. The number (N) of photons used to excite chlorophyll molecules per reaction center was controlled between 0.06 and 80. The 1/e lifetime was ca. 25 ps for N 1. which is much shorter than previously measured lifetimes of photosystem I particles. The initial fluorescence intensity saturated at higher excitation intensities (N ≲ 1). This was interpreted in terms of interaction and annihilation among excited chlorophyll molecules which occur almost entirely within the duration of a laser flash. The spectrum‐resolved fluorescence decay was faster at 690 than at 680 nm. This implies that two kinds of antenna chlorophylls, apart from and in close proximity to P700, have different lifetimes. Upon heat treatment a component with a much longer fluorescence decay time was observed. The growth of this component upon heat treatment at increasing temperatures showed a correlation with a decrease in the amount of P700 that could be photooxidized.