ABSTRACT
In this chapter, we will discuss the fundamental aspects of electron transport of life processes. The chemiosmotic model is fully consistent with the Marcus model for ET and proton transfer (PT). ET takes place between π-systems as well as between metal ions, or between metal ions and π-systems. A biological chemical reaction that occurs perhaps a thousand times per second must work in a conserved structure and ET reactions are therefore well suited, since bond lengths, bond angles, and solvent structures are only slightly modi›ed during the reaction. Most ET steps occur in a chain on the time scale of microseconds (μs), and no reaction step needs to be faster than a suf›ciently fast rate-determining reaction step. Among biological ET reactions, those related to the charge separation in photosynthesis are a million times faster. But the latter reactions are photoreactions, where the competition with side reactions in the excited state demands high rates for the “useful” reactions. Chlorophyll molecules are used, probably because the change of structure when it is excited or ionized is very small. Photosynthetic ET will be discussed in Chapter 15.
