A comparative study of the photosystem II membrane proteins with natural lipids in monolayers

Monolayers of the photosystem II core particles (PSIICP) and light-harvesting complexes from spinach and their mixtures with the following lipids: phosphatidylethanolamine, phosphatidylcholine, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol and digalactosyldiglyceride (DGDG) were prepared and investigated. Strong interaction between PSIICP and DGDG was found as compared to other lipids. The standard protein bands for PSIICP were found by electrophoresis (SDS-PAGE) in all samples taken from the interface of the mixed lipid–protein monolayers, but not in those from the aqueous subphase. At surface pressure 40 mN/m, these protein bands remained the same only for mixed monolayers with DGDG. The damage of PSIICP by illumination in the lipid monolayers and strong binding of the remaining polypeptides with DGDG were shown.