Chromophore-protein interactions and the function of the photosynthetic reaction center: A molecular dynamics study

H. Treutlein, K. Schulten, A. T. Brünger, M. Karplus, J. Deisenhofer, H. Michel

Research output: Contribution to journalArticlepeer-review

104 Scopus citations


The coupling between electron transfer and protein structure and dynamics in the photosynthetic reaction center of Rhodopseudomonas viridis is investigated. For this purpose molecular dynamics simulations of the essential portions (a segment of 5797 atoms) of this protein complex have been carried out. Electron transfer in the primary event is modeled by altering the charge distributions of the chromophores according to quantum chemical calculations. The simulations show (i) that fluctuations of the protein matrix, which are coupled electrostatically to electron transfer, play an important role in controlling the electron transfer rates and (ii) that the protein matrix stabilizes the separated electron pair state through rapid (200 fs) and temperature-independent dielectric relaxation. The photosynthetic reaction center resembles a polar liquid in that the internal motions of the whole protein complex, rather than only those of specific side groups, contribute to i and ii. The solvent reorganization energy is about 4.5 kcal/mol. The simulations indicate that rather small structural rearrangements and changes in motional amplitudes accompany the primary electron transfer.

Original languageEnglish (US)
Pages (from-to)75-79
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Issue number1
StatePublished - 1992

ASJC Scopus subject areas

  • General


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