Time-dependent changes in the carotenoid composition and preferential binding of spirilloxanthin to the reaction center and anhydrorhodovibrin to theLH1 antenna complex in Rhodobium marinum

Carotenoids were isolated from the cells of Rhodobium marinum, and their st ructures were determined by mass spectrometry and H-1 nuclear magnetic reso nance spectroscopy; the carotenoids include lycopene, rhodopin, anhydrorhod ovibrin, rhodovibrin and spirilloxanthin. Time-dependent changes in the car otenoid composition in the reaction center (RC) and the light-harvesting co mplex 1 (LH1) were traced by high-performance liquid chromatography analysi s of the extracts. The carotenoid composition changed according to the spir illoxanthin biosynthetic pathway. However, spirilloxanthin having the longe st conjugated chain was always preferentially bound to the RC, and anhydror hodovibrin and other precursors to the LH1.