ARTIFICIAL ALTERATIONS OF FLUIDITY OF PEA THYLAKOID MEMBRANES AND ITSEFFECT ON ENERGY-DISTRIBUTION BETWEEN BOTH PHOTOSYSTEMS

Two different membrane perturbing agents - cholesterol and benzyl alco hol were applied to modify the fluidity of pea thylakoid membranes. We ll pronounced decrease of membrane fluidity was observed upon increasi ng of cholesterol added. Rigification of thylakoid membranes was accom panied by reduction of cation-induced increase of light-scattering int ensity and results in lower extent of increase of spillover upon catio n induced stack-unstack transition. Thylakoid membranes, treated with local anesthetic benzyl alcohol, showed an increase of membrane fluidi ty, but approximately the same behavior as untreated thylakoids in res pect to the light scattering intensity dependence on cation concentrat ion. Upon stack-unstack transition the observed changes of energy dist ribution for benzyl alcohol treated thylakoids are similar to those fo r controls. The data are discussed in terms of influence of membrane f luidity on lateral reorganization of pigment-protein complexes.