Comparative Studies of Protein Properties and Bacteriochlorophyll Contents of Bacteriochlorophyll-Protein Complexes from Spectrally Different Types of Rhodopseudomonas palustris

Abstract

The amino acid compositions, constituent polypeptides and bacteriochlorophyll (Bchl) contents of two kinds of Bchl-protein complexes isolated from Rhodopseudo-monas palustris were examined. Spectrally dissimilar intracytoplasmic membranes obtained from cells cultured under different conditions were used as starting materials. The B870-reaction center complex was consistent in its amino acid composition, constituent polypeptides and Bchl content, as well as in its near-infrared absorption spectrum. B800–850 complexes from the different types of intracytoplasmic membrane varied in their absorption spectra, though they had similar amino acid compositions and were comprised of basically similar kinds of polypeptides with variations only in the levels of some minor constituent polypeptides. The B800–850 complex with a low absorption peak at 850 nm had a Bchl content 1.3 times greater than the B800–850 complex with a high absorption peak at 850 nm. These results indicate that the B800–850 complex from R. palustris contains more components (both polypeptides and Bchl molecules) than the B800–850 complexes from Rhodopseudomonas capsulata and Rhodopseudomonas sphaeroides.