ORGANIZATION AND FUNCTIONAL-ACTIVITY OF INTERGRANAL AND GRANAL FRAGMENTS OF PEA THYLAKOIDS

Two fractions of light particles enriched in photosystem I and a fract ion of heavy,granal particles were obtained from isolated pea (Pisum s ativum L.) thylakoids. The composition of pigment-protein complexes, s pectra of low-temperature chlorophyll fluorescence and excitation spec tra of long-wave chlorophyll fluorescence, the rates of light-induced oxidation and dark reduction of P700, photochemical activities of phot osystem I and photosystem II, and induction curves of chlorophyll fluo rescence were measured in these particles. It was found that photosyst em I complexes in the three fractions of thylakoid fragments differed by the size of their light-harvesting antennae and the rate of dark re duction of P700(+). The last characteristic was sensitive to 3-(3,4-di chlorophenol)-1,1-dimethylurea, an inhibitor of linear electron transp ort, only in granal particles, which indicates the presence of electro n transfer between photosystem I and photosystem II in these particles . Characteristics of photosystem II complexes differed in the three fr actions of subchloroplast particles. The comparison of our results and data in the literature allowed us to identify the two fractions of li ght particles as fragments of intergranal thylakoids and stroma-expose d regions of granal thylakoids.