CONFIGURATIONS OF CAROTENOIDS IN THE REACTION CENTER and THE LIGHT‐HARVESTING COMPLEX OF Rhodospirillum rubrum. NATURAL SELECTION OF CAROTENOID CONFIGURATIONS BY PIGMENT PROTEIN COMPLEXES

Abstract

Abstract— Carotenoids extracted from the reaction center (RC), the light‐harvesting complex (LH), and the chromatophore membrane of Rhodospirillum rubrum SI were analyzed by high‐performance liquid chromatography. The chemical structures and the configurations of major components were determined by means of mass, Raman, electronic absorption and 1 H‐NMR spectroscopy. The results indicated: (1) 15‐ cis ‐spirilloxanthin is bound to RC; (2) both all‐frans‐spirilloxanthin and aII‐(ran.s‐3,4‐dihydrospirilloxanthin are bound to LH and (3) 13‐cK‐spirilloxanthin is additionally present in the chromatophore membrane. The natural selection of the carotenoid configurations, i.e. 15‐ris by RC and aW‐trans by LH, is discussed in relation to the physiological functions and the photophysical properties of isomeric carotenoids.