Femtosecond kinetics of electron transfer in the bacteriochlorophyll(M)-modified reaction centers from Rhodobacter sphaeroides (R-26).
Formation of the vibronic wavepacket by 90-fs excitation of the primary electron donor P in bacteriochlorophyll(M)-modified reaction centers is shown to induce nuclear motions accompanied by (1) oscillation of the stimulated emission from excited primary electron donor P* and (2) wavepacket motions leading to electron transfer at 293 K from P* to bacteriochlorophyll (B(L)) and then to bacteriopheophytin (H(L)). The latter motions have low frequency (about 15 cm-1) and are related to protein-nuclear motions which are along the reaction coordinate. When the wavepacket approaches the intersection of the reactant (P*B(L)) and product (P+B(L)-) potential energy surfaces (approximately 1.5 ps delay), about 60% of P* is converted to the P+B(L)- state. The P+H(L)- state formation is delayed by approximately 2 ps with respect to that of P+B(L)-. It is suggested that the wavepacket is transferred to and moves also slowly on the P+B(L)- potential energy surface and approaches the intersection of the surfaces of P+B(L)- and P+H(L)- within approximately 2 ps (approximately 8 cm-1), indicating the electron transfer to H(L).
Streltsov
A M
AM
Laboratory of Photobiophysics, Belozersky Institute of Chem. Phys. Biology of Moscow State University, Russian Federation.
Yakovlev
A G
AG
Shkuropatov AYa
Shuvalov
V A
VA
D001429:Bacteriochlorophylls / Q000378:metabolism*; D004579:Electron Transport; D007700:Kinetics; D045342:Light-Harvesting Protein Complexes; D010674:Pheophytins / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000378:metabolism*; D012242:Rhodobacter sphaeroides / Q000378:metabolism*; D013055:Spectrophotometry, Infrared
D001429:Bacteriochlorophylls; D045342:Light-Harvesting Protein Complexes; D010674:Pheophytins; D045322:Photosynthetic Reaction Center Complex Proteins; C006678:bacteriopheophytin