Spectroelectrochemical Determination of the Redox Potentials of Pheophytin a and Primary Quinone QA in Photosystem Ⅱ from Thermosynechococcus Elongatus

摘要

Thin-layer cell spectroelectrochemistry was applied for the first time to measure the redox potentials of pheophytin (Phe) a and the primary quinone QA in photosystem (PS) Ⅱ core complexes from a thermophilic cyanobacterium Thermosynechococcus elongatus. The determined potentials for oxygenevolving PS Ⅱ from a T. elongatus wild type strain were -522 ± 3 mV and -140 ± 2 mV for Phe a and QA, respectively. Based on the determined values together with kinetic analytical data in literature, a renewed diagram is proposed for the energetics in PS Ⅱ, and further, modification of the redox properties for acclimation to cultivate conditions is also discussed.