chlorophyll-a and iodonaphthylazide

Chromatophores of the photosynthetic bacterium Rhodospirillum rubrum and isolated reaction centers were labeled with the lipophilic membrane marker 5-[125I]iodonaphthyl-1-azide. The two smaller reaction center proteins L and M bind more label than the larger subunit H, a fact supporting the proposed localisation of the 3 subunits obtained with hydrophilic labels. Besides these integral proteins the lipids, among them mainly the pigments and the quinones, are highly labeled suggesting a hydrophobic environment around these molecules and a preferred reactivity to iodonaphthylazide. Such a hydrophobic environment may be of great importance for the function of the photosynthetic reaction centers especially for the charge separation and the primary reactions in electron transport.

Topics: Azides; Bacterial Chromatophores; Cell Membrane; Chlorophyll; Cold Temperature; Histocytochemistry; Iodine Radioisotopes; Membrane Lipids; Membrane Proteins; Naphthalenes; Rhodospirillum