Enthalpy/entropy driven activation of the first interquinone electron transfer in bacterial photosynthetic reaction centres embedded in vesicles of phisiologically important lipids

The thermodynamics and kinetics of light-induced electron transfer in bacterial photosynthetic RCs are sensitive to physiologically important lipids (phosphatidylcholine, cardiolipin and phosphatidylglycerol) in the environment. The analysis of the temperature-dependence of the rate of the P(+)Q(A)(-)Q(B)-> P(+)Q(A)Q(B)(-) interquinone electron transfer revealed high enthalpy change of activation in zwitterionic or neutral micelles and vesicles and low enthalpy change of activation in vesicles constituted of negatively charged phospholipids. The entropy change of activation was compensated by the changes of enthalpy, thus the free energy change of activation (approximate to 500 meV) did not show large variation in vesicles of different lipids. (c) 2006 Elsevier B.V. All rights reserved.