Published on Web 01/13/2006
The A-FX to FA/B Step in Synechocystis 6803 Photosystem I Is Entropy Driven Harvey J. M. Hou† and David Mauzerall*,‡ Contribution from the Department of Chemistry, Gonzaga UniVersity, 502 East Boone AVenue, Spokane, Washington 99258, and The Rockefeller UniVersity, 1230 York AVenue, New York, New York 10021 Received July 20, 2005; E-mail:
[email protected] Abstract: We have previously reported the enthalpy and volume changes of charge separation in photosystem I from Synechocystis 6803 using pulsed photoacoustics on the microsecond time scale, assigned to the electron-transfer reaction from excited-state P700* to FA/B iron sulfur clusters. In the present work, we focus on the thermodynamics of two steps in photosystem I: (1) P700* f A1-FX (
