Measurement of the redox state of the plastoquinone pool in cyanobacteria

Abstract

<p>Here, we developed a method for measuring the in vivo redox state of the plastoquinone (PQ) pool<br />in the cyanobacteria <i>Synechocystis</i> sp. PCC 6803. Cells were illuminated on a glass fiber filter, PQ<br />was extracted with ethyl acetate and determined with HPLC. Control samples with fully oxidized<br />and reduced photoactive PQ pool were prepared by far-red and high light treatments, respectively,<br />or by blocking the photosynthetic electron transfer chemically before or after PQ in moderate<br />light. The photoactive pool comprised 50 % of total PQ. We find that the PQ pool<br />of cyanobacteria behaves under light treatments qualitatively similarly as in plant chloroplasts, is<br />less reduced during growth under high than under ambient CO2 and remains partly reduced in<br />darkness.<br /></p>