Photochemically induced dynamic nuclear polarization in the reaction center of the green sulphur bacterium Chlorobium tepidum observed by 13C MAS NMR

Photochemically induced dynamic nuclear polarization has been observed in reaction centres of the green sulphur bacterium Chlorobium tepidum by 13C magic-angle spinning solid-state NMR under continuous illumination with white light. An almost complete set of chemical shifts of the aromatic ring carbons of a BChl a molecule has been obtained. All light-induced 13C NMR signals appear to be emissive, which is similar to the pattern observed in the reaction centers of plant photosystem I and purple bacterial reaction centres of Rhodobacter sphaeroides wild type. The donor in RCs of green sulfur bacteria clearly differs from the substantially asymmetric special pair of purple bacteria and appears to be similar to the more symmetric donor of photosystem I.