| Popis: |
This chapter discusses electron transfer mechanisms in reaction centers. Biological electron transfer has been made possible by the solution of the X-ray diffraction structure of two photosynthetic reaction centers and by extensive measurements on the free-energy dependence of photosynthetic electron transfer reactions. However, a relatively simple form of electron transfer theory is sufficient to define the rate of the majority of intraprotein electron transfer reactions within the uncertainty currently associated with measuring the fundamental parameters of distance, free energy, and reorganization energy. This chapter presents a first-order description of the important parameters of intraprotein electron transfer and presents a list of basic principles of electron transfer protein design. A simple equation derived from quantum mechanical perturbation theory, known as Fermi's Golden Rule, provides a good first-order description of the rate of nonadiabatic electron transfer. The extensive free-energy dependence of the quinone electron transfer reactions in the bacterial photosynthetic reaction centers provides the best illustration of how the Franck–Condon factors and the optimal rates of intraprotein electron transfer are determined experimentally. |
