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Excited‐State Energy Level Does Not Determine the Differential Effect of Violaxanthin and Zeaxanthin on Chlorophyll Fluorescence Quenching in the Isolated Light‐Harvesting Complex of Photosystem II
Author(s) -
Ruban Alexander V.,
Phillip Denise,
Young Andrew J.,
Horton Peter
Publication year - 1998
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.1751-1097.1998.tb05291.x
Subject(s) - violaxanthin , zeaxanthin , photosystem ii , excited state , photochemistry , quenching (fluorescence) , non photochemical quenching , fluorescence , chlorophyll fluorescence , light harvesting complexes of green plants , antheraxanthin , chemistry , chlorophyll , photosynthesis , chlorophyll a , photosystem i , lutein , atomic physics , carotenoid , physics , optics , biochemistry , organic chemistry , food science
— The mechanism of action of xanthophyll cycle carotenoids in controlling the quenching of chlorophyll fluorescence in the major light‐harvesting complex of photosystem II (LHCIIb) has been investigated. Auroxanthin, a diepoxy carotenoid with 7 conjugated carbon double bonds, violaxanthin (9 conjugated double bonds) and zeaxanthin (11 conjugated double bonds) have been compared with regard to their effects in vitro on fluorescence quenching and LHCIIb oligomerization. It was found that auroxanthin stimulated fluorescence quenching, similar to the effect of zeaxanthin and in contrast to the inhibition caused by violaxanthin. Auroxanthin caused an increase in the oligomerization of LHCIIb and an increase in relative emission of long‐wavelength fluorescence at 77 K. It is concluded that auroxanthin can mimic the effect of zeaxanthin on LHCII, strongly suggesting that the xanthophyll cycle carotenoids control quenching in vitro by an indirect structural effect and not by direct quenching of chlorophyll excited states.