Isolation And Characterization Of Brown Algae Pigment-protein Complexes

The separating technique of the light active pigment-protein complexes from brown algae Undaria pinnatifida was developped in this paper. The results of SDGC separation were observed and the separating technique of brown algae was established. Five pigment-protein complexes were isolated by centrifugation on discontinuous sucrose density gradient of the SDS-treated thylakoid membrane. The best separation was obtained with detergent SDS (SDS:Chl=20:l, solubilized 20 min at 4'C), sucrose density gradient (10,15,20,30,40,50,60% w/w).Absorption, fluorescence emission and excitation spectra of five pigment-protein complexes were determined. Photosynthetic electron transfer was measured from the DCIP photoreduction. P700 concentration was assayed from the ferricyanide -oxdised minus ascorbate-reduced difference spectrum. 10% and 15% sucrose layers were identified as light harvesting complexes; 20% and 30% sucrose layers were identified as composed of active PS II particles; 40% sucrose layer represented rather pure PS I complex. The PS II native fractions(20% and 30%) were loaded onto a DEAE column.The fraction eluted with 150 mM NaCl was presented DCIP reduction activity and was highly depleted in Chi c and xanthophylls, and as such could be considered a PS II core complex.The fluorescence spectra of brown algae thylakoid membrane and PS I complex varied from higher plants, they had no fluorescence emission maximum at 730 nm. we concluded that 730 nm fluorescence was no more a symbol of PS I .