Femtosecond kinetics of electron transfer in the bacteriochlorophyll(M)-modified reaction centers from Rhodobacter sphaeroides (R-26)

FEBS Lett. 1996 Mar 25;383(1-2):129-32. doi: 10.1016/0014-5793(96)00113-5.

Abstract

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).

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Bacteriochlorophylls / metabolism*
  • Electron Transport
  • Kinetics
  • Light-Harvesting Protein Complexes
  • Pheophytins / metabolism
  • Photosynthetic Reaction Center Complex Proteins / metabolism*
  • Rhodobacter sphaeroides / metabolism*
  • Spectrophotometry, Infrared

Substances

  • Bacteriochlorophylls
  • Light-Harvesting Protein Complexes
  • Pheophytins
  • Photosynthetic Reaction Center Complex Proteins
  • bacteriopheophytin