[Optimization of isolation conditions for three types of pigment protein-lipid complexes from chloroplasts during...

The maximal total release of pigment protein-lipid complexes (PPLC) during their isolation from pea chloroplasts was achieved by 1-hr solubilization with Triton X-100, the Triton:chlorophyll (T/Chl) ratio being 50 mg/mg/ml. The total yield of the reaction center complexes (sigma PPLC RC) was 22,3%, whereas that of the auxiliary light-accumulating complex (ALA-PPLC) was approximately 32% with respect to Chl. An increase in the solubilization time and of the T/Chl ratio resulted in dissociation of ALA-PPLC. On the contrary, the reaction center complexes steadily maintained their composition and high photochemical activity within a wide range of T/Chl during 24--28 hrs of solubilization. The purest preparations of PPLC RC of phostosystem I (PS-I) were obtained by 24 hr-incubation (T/Chl = 80); their Chl/P700 ratio after a single fractionation on DEAE-cellulose was equal to 36. A considerable increase of T/Chl and of the solubilization time hampered the chromatographical separation of PPLC RC of PS-I and PPLC RC of PS-II. The optimal conditions for isolation of PPLC RC of PS-I and PPLC RC of PS-II were: solubilization at T/Chl 80--120 and prolongation of incubation time from 5 to 7 hrs. The photochemical activity of the complexes obtained was maximal and correlated with the minimal content of admixture P700 (1 molecule of P700 per 450--500 molecules of Chl.).