MULTIDIMENSIONAL CP-MAS C-13 NMR OF UNIFORMLY ENRICHED CHLOROPHYLL

The progress toward structure refinement of solid-type uniformly C-13 enriched ([U-C-13]) chlorophyll-containing biological preparations is summarised. Solid state carbon chemical shifts of aggregated [U-C-13] bacteriochlorophyll (BChl) c in intact chlorosomes of Chlorobium tepid um and in [U-C-13] BChl c aggregates were determined by the applicatio n of homonuclear (C-13-C-13) magic angle spinning (MAS) NMR dipolar co rrelation spectroscopy. It was found that the arrangement of BChl c mo lecules in the chlorosomes and in the aggregates is highly similar, wh ich provides convincing evidence that self-organisation of the BChl c is the main mechanism to support the structure of the chlorosomes. Add itionally, high held 2-D (H-1-C-13) and 3-D (H-1-C-13-C-13) dipolar co rrelation spectroscopy was applied to determine solid state proton che mical shifts of aggregated [U-C-13] BChl c in intact chlorosomes. From the high-field assignments, evidence is found for the existence of at least two well-defined interstack arrangements. (C) 1998 Elsevier Sci ence B.V. All rights reserved.