CONFIGURATIONS OF NEUROSPORENE ISOMERS ISOLATED FROM THE REACTION CENTER AND THE LIGHT‐HARVESTING COMPLEX OF Rhodobacter spheroides G1C. A RESONANCE RAMAN, ELECTRONIC ABSORPTION, AND₁H‐NMR STUDY

Abstract

Abstract— HPLC analysis of neurosporene extracted from the chromatophore membranes of Rhodobacter spheroides G1C showed two isomeric components 1 and 2. Extract from the light‐harvesting complex (LH) gave only component 2, while extract from the reaction center (RC) mainly gave component 1. Both components were isolated, and their configurations were determined by means of (1) resonance Raman, (2) electronic absorption, and (3) 1 H‐HMR spectroscopy. The configuration of component 2 originating from LH was determined to be all ‐trans and that of component 1 from RC was determined to be 15‐ cis . Thus, our previous configurational prediction of this particular carotenoid bound to RC, by means of resonance Raman spectroscopy, to be 15‐cis [Y. Koyama, T. Takii, K. Saiki and K. Tsukida, Photobiochem. Photobiophys. 5 (1983)139–150] is confirmed.