Correlation of electronic carotenoid–chlorophyll interactions and fluorescence quenching with the aggregation of native LHC II and chlorophyll deficient mutants

The aggregation dependent correlation between fluorescence quenching and the electronic carotenoid–chlorophyll interactions, ϕ Coupling Car S 1 - Chl , as measured by comparing chlorophyll fluorescence observed after two- and one-photon excitation, has been investigated using native LHC II samples as well as mutants lacking Chl 2 and Chl 13. For native LHC II the same linear correlation between ϕ Coupling Car S 1 - Chl and the fluorescence quenching was observed as previously reported for the pH and Zea-dependent quenching of LHC II [1] . In order to elucidate which carotenoid–chlorophyll pair might dominate this correlation we also investigated the mutants lacking Chl 2 and Chl 13. However, also with these mutants the same linear correlation as for native LHC II was observed. This provides indication that these two chlorophylls play only a minor role for the observed effects. Nevertheless, we also conclude that this does not exclude that their neighboured carotenoids, lutein 1 and neoxanthin, might interact electronically with other chlorophylls close by.