Abstract
The esterifying substituent at the 172-position of chlorophylls has been less studied, because of its indirect attaching to their π-conjugated skeletons. However, this relatively large substituent plays an important role in constructing photosynthetic apparatuses. The structures and distribution of its biosynthetic intermediates possessing a GG, DHGG, or THGG moiety in bacteriochlorophyll-a were carefully investigated for a purple bacterium, Rhodopseudomonas (Rps.) palustris, which excessively accumulated the intermediates. As the result, these intermediates of BChl-a were apparently localized in different types of photosynthetic apparatuses (LH2, LH4, and RC-LH1). In this study, we analyzed the structures and distribution of the corresponding bacteriopheophytin (BPhe). We successfully isolated the RC from Rps. palustris species for the first time. The composition of BPhe-a having different 172-ester groups in the RC was analyzed by LC-MS. The content of BPhe-a having a matured phytyl group was larger than that of BChl-a, and BPhe-a having a THGG group was first identified in the RC as a photosynthetically active pigment.
