STRUCTURES OF CHLOROSOMES AND AGGREGATED BCHL-C IN CHLOROBIUM-TEPIDUM FROM SOLID-STATE HIGH-RESOLUTION CP/MAS C-13 NMR

Cross polarization/magic angle spinning (CP/MAS) C-13 (solid state high resolution) NMR spectra were observed for chlorosomes and BChl c aggregates. Similarity of both kinds of spectra (except for some signals assignable to proteins and lipids in chlorosomes) indicates that BChl c's in chlorosomes are present just as in synthetic BChl c aggregates. Chemical shifts for C13(1) carbonyl and C3(1) hydroxylethyl carbons indicate hydrogen bonding between them. Comparison of solution and solid state C-13 NMR chemical shifts shows the five coordinated nature of BChl c aggregates. Some chemical shift differences were attributable to ring currents shifts. Their comparisons with calculated ring current shift values predicted structures for the aggregates. Cross polarization dynamics of the CP/MAS C-13 NMR signals explored dynamic and structural nature of the BChl c aggregates.