Analysis of the electronic structure of the Special Pair of a Bacterial Photosynthetic Reaction Center by 13C Photochemically Induced Dynamic Nuclear Polarization Magic-Angle Spinning NMR Using a Double-Quantum Axis

摘要: The origin of the functional symmetry break in bacterial photosynthesis challenges since several decades. Although structurally very similar, two branches cofactors reaction center (RC) protein complex act differently. Upon photochemical excitation, an electron is transported along one branch, while other remains inactive. Photochemically induced dynamic nuclear polarization (photo-CIDNP) magic-angle spinning (MAS) 13 C NMR revealed that bacteriochlorophyll forming "Special Pair" donor dimer are already well distinguished electronic ground state. These previous studies relying solely on C-13 correlation experiments as radio-frequency-driven recoupling (RFDR) and dipolar-assisted rotational resonance (DARR). Obviously, chemical-shift assignment difficult a tetrapyrrole macrocycles, having eight pyrrole rings similar chemical shifts. To overcome this problem, INADEQUATE type experiment using POST C7 symmetry-based approach applied to selectively isotope-labeled RC Rhodobacter (R.) sphaeroides wild (WT). We, therefore, were able distinguish unresolved sites macromolecular dimer. obtained pattern in-line with concentric assembly negative charge within common Special Pair supermolecule