ISOLATION OF MEMBRANE-BOUND LIGHT-HARVESTING-COMPLEXES FROM THE DINOFLAGELLATES HETEROCAPSA-PYGMAEA AND PROROCENTRUM-MINIMUM

We have isolated Chl a-Chl c-carotenoid binding proteins from the dino flagellates Prorocentrum minimum and Heterocapsa pygmaea grown under h igh (500 mu mol m(-2) s(-1), HL) and low (35 mu mol m(-2) s(-1), LL) l ight conditions. We compared various isolation procedures of membrane bound light harvesting complexes (LHCs) and assayed the functionality of the solubilized proteins by determining the energy transfer efficie ncy from the accessory pigments to Chl a by means of fluorescence exci tation spectra. The identity of the newly isolated protein-complexes w ere confirmed by immunolo,oical cross-reactions with antibodies raised against the previously described membrane bound Chl a-c proteins (Boc zar et al. (1980) FEES Lett 120: 243-247). Spectroscopic analysis demo nstrated the relatedness of these proteins with the recently described Chl-a-c(2)-peridinin (ACP) binding protein (Hiller et al. (1993) Phot ochem Photobiol 57: 125-131; Iglesias Prieto et al. (1993) Phil Trans R Soc London B 338: 381-392). The water-soluble peridinin-Chl a bindin g-protein (PCP) was not detectable in P. minimum. Two functional forms of ACP with different pigmentation were isolated. A variant of ACP wh ich was isolated from high-light grown cells, that specifically binds increased amounts of diadinoxanthin was compared to the previously des cribed ACPs that bind proportionately more peridinin.