13C Photo-CIDNP MAS NMR on the LH1-RC Complex of Rhodopseudomonas acidophila

Abstract

The electronic structures of the cofactors involved into the primary radical pairs in LH1-bound RCs of Rhodopseudomonas acidophila and in isolated RCs of Rhodobacter sphaeroides are compared by photochemically induced dynamic nuclear polariziation (photo-CIDNP) magic-angle spinning (MAS) NMR. Only minor differences in the electronic ground-state of the donor and a very similar distribution of the electron spin density in the radical pair state is observed. On the other hand, the ratio between donor and acceptor signals appears to be slightly different. The origin of the effect is discussed.