We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
The nature of the lower excited state of the special pair of bacterial photosynthetic reaction center of Rhodobacter Sphaeroides and the dynamics of primary charge separation.
- Authors
Ivashin, N.; Shchupak, E.
- Abstract
Quantum-chemical calculations of the structure in the ground and lower singlet excited states and the vibrations (in the ground state) of special pair P of photosynthetic reaction center of purple bacteria (RCPb) Rhodobacter Sphaeroides, consisting of two bacteriochlorophyll molecules P and P, have been carried out. It is shown that excitation of the special pair is followed by fast relaxation dynamics, accompanied by the transformation of the initial P* state into the P P state (δ ~ 0.5) with charge separation. This behavior is due to the presence of several nonplanar vibrations with participation of the acetyl group of macrocycle P in the nuclear wave packet on the potential surface of the P* state; these vibrations facilitate destabilization of the lowest unoccupied molecular orbital (LUMO) and highest occupied molecular orbital (HOMO) of the macrocycle P and formation of the P P state. The structural transformations in the P* state are due to its linking character in the contact region of the acetyl group-containing pyrrole rings of P and P. The transition from the P* state to specifically the P P state is related to the fact that the acetyl group P is involved in the intermolecular hydrogen bond with amino acid residue His; for this reason, this group and the pyrrole ring linked with it can hardly participate in structural transformations. The electronic matrix element Н of the electron transfer from the special pair in the P P state to a molecule of accessory bacteriochlorophyll В greatly exceeds that for the transfer to В. This circumstance and the fact that the P P state is energetically more favorable than the P* state facilitate the preferred directionality of the electron transfer in RCPb Rhodobacter Sphaeroides with participation of the cofactors located in its subunit L.
- Subjects
EXCITED states; PHOTOSYNTHETIC reaction centers; RHODOBACTER sphaeroides; QUANTUM chemistry; BACTERIOCHLOROPHYLLS
- Publication
Optics & Spectroscopy, 2016, Vol 121, Issue 2, p181
- ISSN
0030-400X
- Publication type
Article
- DOI
10.1134/S0030400X16080087