Isolation And Characteristics Of Pigment-protein Complexes In Haematococcus Pluvialis

Haematococcus pluvialis is a unicellular biflagellated green alga.Its life history mainly includes motile green cell stage,non-motile green cell stage and red resting cell stage.Under stress conditions,H.pluvialis can accumulate massive astaxanthin,redden the cells.H.pluvialis strain CG-11 was used in this study.The pigment-protein complexes were first time isolated from green cells and red cells,respectively.Their spectrum characteristics were investigated.The main results were summarized as follows:(1) Analysis of spectrum characteristics of different types of cells from H.pluvialis:The red cells possess strong absorption between 450 nm and 550 um compared with green cells.The fluorescence emission spectra were almost the same within the two types of cells excited by 436 nm and 465 nm wavelength of lights.Three emission peaks were detected,which located at 682 nm,693 nm and 712 nm respectively.The emission peaks of green cells exhibited at 710 nm and 730 nm while red cells only at 730 nm excited by 490 nm wavelength of light.These results indicated that there are differences in the structure,composition and pigment-protein complexes' arrangement of photosystems between H.pluvialis CG-11 green cells and red cells.(2) Five pigment-protein complex bands were first time separated from green cells preparations by using disc SDS-PAGE electrophoresis.According to the analysis of 77 K spectral characteristics,these complexes might be CP Ia,CP I,CPa,LHCP₁ and LHCP₂ from top to bottom of the band existed in disc SDS-PAGE,while the last two bands were free pigments. However,four pigment-protein complexes from the red cells of Haematococcus pluvialis CG-11 were isolated,which were CP Ia,CP I,Cpa and LHCP₁.(3) CPâ… a and CPâ… were pigment-protein complexes that both belong to PSâ… .The emission peaks of CP Ia in red cells was at 717 nm,while it was at 708 in the green cells.These two emission peaks were different from 730 nm in green higher plants.The emission peaks of CPâ… in green cells was at 713 nm,while in red cells was 725 um,both were similar to 717-722 nm in most green alga and higher plants.(4) The excitation spectra of light-harvesting complexes in red and green H.pluvialis CG-11 cells varied remarkably.Excitation spectra of green cells' LHCP₁ exhibited peaks at 438 nm,480 nm and 489 nm,but,red cells' LHCP₁ had another peak at 457 nm.Astaxanthin was detected in the LHCP₁ from red cells by using HPLC,which suggested that astaxanthin might be combined with pigment-protein complexes in red cells.(5) The molecular weight of polypeptides in thylakoid were similar in red and green cells of H.pluvialis CG-11,which were between 20-97 kD.