INTRAMEMBRANE CHARGE-TRANSFER REACTIONS - THE MEMBRANE AS A DIELECTRIC MEDIUM

Intramembrane charge transfer was considered in the framework of a thr ee-phase model, which describes the membrane as a layer with a low die lectric constant (hydrocarbon chains of lipids, hydrophobic segments o f transmembrane proteins) surrounded on two sides by layers of interme diate polarity (lipid polar heads, protein hydrophilic segments) and f urther by aqueous electrolyte solutions. Expressions were derived for the electric potential distribution, the solvation energy of ions insi de the membrane, and the reorganization energy for the intramembrane c harge transfer. By way of example, the results were used to calculate the reorganization energy for electron transfer from the bacteriopheop hytin anion-radical to primary quinone in the bacterial photosynthetic reactive center.