ABSTRACT
Pigment-lipoprotein B890 complexes containing reaction center and "light-focusing" bacteriochlorophyll a were isolated from photosynthetic membranes of sulfur (Chromatium minutissimum) and non-sulfur (Rhodopseudomonas palustris) purple bacteria after the treatment with Triton X-100. The molecular weights of complexes were evaluated using several methods (200 000-300 000). By means of electron microscopy the sizes of complexes were found to be about 80 A. On the air-water interface hexagonal packing of complexes was observed. The chemical compositions of complexes are very similar except bacteriochlorophyll a whose specific content is somewhat higher in Chromatium minutissimum. The protein composition of complexes was studied and the molecular weights of proteins were estimated by SDS-gel electrophoresis. The results obtained show significant similarities in molecular organization of B890 complexes isolated from sulfur (Chromatium minutissimum) and non-sulfur (Rhodopseudomonas palustris) purple bacteria.
Subject(s)
Bacterial Proteins , Chromatium/analysis , Lipoproteins , Pigments, Biological , Rhodopseudomonas/analysis , Bacteriochlorophylls , Chemical Phenomena , Chemistry , Cytochrome c Group , Microscopy, Electron , Molecular Weight , Species Specificity , Spectrum AnalysisABSTRACT
Light-harvesting pigment-lipoprotein complexes from sulfur (Chromatium minutissimum) and non-sulfur (Rhodopseudomonas palustris) purple bacteria are isolated and comparatively studied. Electron microscopy was used for determination of the complex size, different methods were employed to estimate their molecular weights and chemical composition. Two small proteins are found in each complex, their molecular weight, molar ratio and their content per complex being studied. Amino acid composition and N-terminal amino acids are determined for both proteins of light-harvesting complex from Chromatium minutissimum. Some common characteristics of the molecular organization of light-harvesting complexes in purple bacteria are discussed.
