Functional Effects of Structural Changes in Photosystem II as Measured by Chlorophyll Fluorescence Kinetics

This chapter discusses the functional effects of structural changes in photosystem II (PS II) as measured by chlorophyll fluorescence kinetics. This is due, in part, to difficulties in purifying membrane-protein complex to homogeneity without a significant loss of properties and activity and to pleiotropic effects, usually accompanying mutations in one of the subunits of a membrane-protein complex. The membrane-protein complex that has been analyzed in most detail by a combination of molecular-genetic and biochemical and biophysical techniques is PS II, the pigment-protein complex that is responsible for the first steps in the photosynthetic electron transport chain, which leads to the light-induced oxidation of water and reduction of plastoquinone. These analysis techniques take advantage of the fact that PS II redox reactions are induced by single photons of light, and thus are easily triggered by single light flashes or by continuous illumination.