The relation between the pigment content of isolated chromatophores and that of the whole cell inRhodopseudomonas spheroides

Abstract

Reports on the relationship between the pigment content of chromato-phores and the whole cells from which they were isolated are reviewed. Chromatophores, isolated in sucrose density gradients from organisms grown at high light intensity or at very low O2 tension in the dark, had a content of bacteriochlorophyll proportional to the pigment content of the cell. Chemical analyses and electron microscopy revealed that these ''chromatophores'' were heavily contaminated with other cellular structures. The inability to obtain pure material from cells grown under these environmental conditions may be due to differences in their internal organization resulting in a different pattern of fragmentation on disruption. When growth was at low to moderate light intensity, chromatophores of constant composition were isolated from cells of different pigment content.