Abstract
A green photosynthetic bacterium, Chlorobium limicola, has an antenna complex called ‘chlorosomes’. Chlorosomes contain ‘the rod elements’ consisting of higher aggregates of bacteriochlorophyll (BChl) c. For structural determination of chlorosomes, it is imperative to establish a method of reassembling chlorosomes consisting of a 1:1 mixture of 13C-BChl c and 12C-BChl c to determine intermolecular 13C···13C dipolar correlations by NMR. In this study, the reassembled chlorosomes were characterized by means of (1) sucrose density-gradient centrifugation, zeta-potential and dynamic light-scattering measurements and electron microscopy to determine the morphology, (2) solid-state NMR, electronic-absorption and circular-dichroism spectroscopies and X-ray diffraction to determine the pigment assembly, and (3) subpicosecond time-resolved absorption spectroscopy to determine the excited-state dynamics.
The results characterized the reassembled chlorosomes with (1) a similar but longer morphological structures, (2) almost the same pigment assembly in the rod elements, and (3) basically the same excited-state dynamics.
The results of structural analysis also will be presented.
