Characterization of Three Forms of Light-Harvesting Chlorophyll a/b-Protein Complexes of Photosystem II Isolated from the Green Alga, Dunaliella salina

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Three forms of light-harvesting chlorophyll a/b-protein complexes of photosystem II (LHC II) were isolated from the thylakoid membranes of Dunaliella salina grown under different irradiance conditions. Cells grown under a low intensity light condition (80μmol quanta m^<-2>s^<-1>) contained one form of LHC II, LHC-L. Two other forms of LHC II, LHC-H1 and LHC-H2, were separated from the cells grown under a high intensity light condition (1, 500μmol quanta m^<-2>s^<-1>). LHC-L and LHC-H1 showed an apparent particle size of 310kDa and contained four polypeptides of 31, 30, 29 and 28kDa. LHC-H2, with a particle size of 110kDa, consisted of 30 and 28kDa polypeptides. LHC-L contained 7.5 molecules of Chl a, 3.2 of Chl b and 2.1 of lutein per polypeptide, analogous to the content in higher plants. LHC-H1, with 5.6 molecules of Chl a, 2.5 of Chl b and 1.8 of lutein per polypeptide was similar to that in the green alga Bryopsis maxima. LHC-L and LHC-H1 maintained high efficiency energy transfer from Chl b and lutein to Chl a molecules. LHC-H2 showed a hihg Chl a/b ratio of 7.5 and contained 3.4 molecules of Chl a, 0.5 of Chl b and 1.4 of lutein per polypeptide. Chl b and lutein could not completely transfer the excitation energy to Chl a in LHC-H2.