Exogenous carotenoids incorporation

A. Incorporation of Exogenous Carotenoids into Reaction Centers from Carotenoidless Mutants...237... 

Boucher et al. (1977) were the first to report that exogenous carotenoids could be incorporated into RCs from carotenoidless bacteria. Using the G9 strain from Ri. rubrum, these authors demonstrated that four carotenoids, spirilloxanthin, spheroidene, spheroidenone and chloroxanthin could be incorporated with nearly 1 1 mol ratios with respect to the primary donor (P 870). The authors showed that the bound carotenoids protected BChl against photodynamic bleaching. An analysis of the absorption and circular dichroism (CD) spectra of the bound carotenoids lead the authors to conclude that the carotenoids adopted a central mono-c/v configuration, a conclusion later confirmed by X-ray diffraction studies on Rhodopseudomonas viridis and Rb. sphaeroides (Yeates et al., 1988 Amoux, 1989 Deisenhofer and Michel, 1989 Ermler et al. 1994 Chapter 6, Fritsch). 

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