Preparation protocols for high-activity photosystem II membrane particles of green algae and higher plants, pH dependence of oxygen evolution and comparison of the S2-state multiline signal by X-band EPR spectroscopy.

Photosystem II (PS II) membrane particles are particularly well suited for various types of spectroscopic investigations on the PS II manganese complex. Here we present: (1) a preparation protocol for PS II membrane particles of higher plants, which yields exceptionally high oxygen-evolution activity due to the use of glycinebetaine as a PS II-stabilizing agent; (2) preparation protocols for highly active PS II membrane particles for the green algae Scenedesmus obliquus and Chlamydomonas reinhardtii; (3) a determination of pH dependence of oxygen evolution for spinach and Scenedesmus; (4) a comparison of the EPR multiline signal observed in the S2-state of green algae and higher plants of PS II membrane particles. A clearly broader type of multiline EPR signal is observed in green algae.