Abstract
Abstract— 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.
Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
