Correlation of paramagnetic states and molecular structure in bacterial photosynthetic reaction centers: the symmetry of the primary electron donor in Rhodopseudomonas viridis and Rhodobacter sphaeroides R-26.

AUTOR(ES)

Norris, J R

RESUMO

The orientation of the principal axes of the primary electron donor triplet state measured in single crystals of photosynthetic reaction centers is compared to the x-ray structures of the bacteria Rhodobacter (Rb.) sphaeroides R-26 and Rhodopseudomonas (Rps.) viridis. The primary donor of Rps. viridis is significantly different from that of Rb. sphaeroides. The measured directions of the axes indicate that triplet excitation is almost completely localized on the L-subunit half of the dimer in Rps. viridis but is more symmetrically distributed (approximately 63% on the L half of the special pair and approximately 37% on the M half) on the dimeric donor in Rb. sphaeroides R-26. The large reduction of the zero field splitting parameters relative to monomeric bacteriochlorophyll triplet in vitro suggests significant participation of asymmetrical charge transfer electronic configurations in the special pair triplet state of both organisms (approximately 23% in Rps. viridis and approximately 13% in Rb. sphaeroides).

Documentos Relacionados

• The Stark effect in reaction centers from Rhodobacter sphaeroides R-26 and Rhodopseudomonas viridis.
• Stark effect spectroscopy of Rhodobacter sphaeroides and Rhodopseudomonas viridis reaction centers
• Relationship between the oxidation potential and electron spin density of the primary electron donor in reaction centers from Rhodobacter sphaeroides
• Electronic structure of Q-A in reaction centers from Rhodobacter sphaeroides. I. Electron paramagnetic resonance in single crystals.
• Primary electron transfer reactions in modified reaction centers from Rhodopseudomonas sphaeroides