Multidimensional CP-MAS 13C 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 tepidum and in [U-C-13] BChl c aggregates were determined by the application of homonuclear (C-13-C-13) magic angle spinning (MAS) NMR dipolar correlation spectroscopy. It was found that the arrangement of BChl c molecules in the chlorosomes and in the aggregates is highly similar, which provides convincing evidence that self-organisation of the BChl c is the main mechanism to support the structure of the chlorosomes. Additionally, high held 2-D (H-1-C-13) and 3-D (H-1-C-13-C-13) dipolar correlation spectroscopy was applied to determine solid state proton chemical 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 Science B.V. All rights reserved.