Abstract
Chlorophyll(Chl)-c3 was characterized by its 7-methoxycarbonyl and 8-vinyl groups. The pigment is thought to be a light-absorbing pigment in photosynthesis together with the other pigments, Chl-a, Chl-c2 and carotenoids. However, the details in the molecular structure and function of Chl-c3 have not yet been raveled, especially for the conformation of the unique acrylic residue at the 17-position as well as the stereochemistry at the chiral 132-position. In this study, we isolated Chl-c3 from coccolithophorid Emiliania huxleyi and determined its molecular structure in detail: the conformation of the acrylate was cisoid around the C17-C171 bond by 1H-1H NOE correlations and the stereochemistry was (132R)-configuration by chiral HPLC and CD spectra. To generalize the natural selection of (132R)-enantiomers of Chls-c, we analyzed several photosynthetic organisms containing Chls-c. Moreover, dependence of fluorescence-quantum-yields of natural Chls-c upon peripheral substituents in a molecule was reported.
