Enthalpy/entropy driven activation of the first interquinone electron transfer in bacterial photosynthetic reaction centers embedded in vesicles of physiologically important phospholipids.
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 ( approximately 500 meV) did not show large variation in vesicles of different lipids.
Milano
Francesco
F
CNR, Istituto per i Processi Chimico-Fisici, Sezione di Bari, c/o Dipartimento di Chimica, Via Orabona, 4 I-70124 Bari, Italy.
Dorogi
Márta
M
Szebényi
Kornélia
K
Nagy
László
L
Maróti
Péter
P
Váró
György
G
Giotta
Livia
L
Agostiano
Angela
A
Trotta
Massimo
M
D016227:Benzoquinones / Q000737:chemistry*; D002308:Cardiolipins / Q000737:chemistry* / Q000378:metabolism; D004579:Electron Transport; D019277:Entropy; D010713:Phosphatidylcholines / Q000737:chemistry* / Q000378:metabolism; D010715:Phosphatidylglycerols / Q000737:chemistry* / Q000378:metabolism; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry* / Q000378:metabolism; D012242:Rhodobacter sphaeroides / Q000737:chemistry / Q000378:metabolism
D016227:Benzoquinones; D002308:Cardiolipins; D010713:Phosphatidylcholines; D010715:Phosphatidylglycerols; D045322:Photosynthetic Reaction Center Complex Proteins; C004532:quinone