Photochemical Activity Of Photosystem Research Articles

Localization of Cytochrome b-559 in the Chloroplast Thylakoid Membranes in Spinach

Cytochrome b-559 was purified from spinach leaves and antibodies were made against it in rabbit. Using affinity-purified, monospecific antibodies, we have found that cytochrome b-559, which is closely associated with the primary photochemical activity of photosystem II, is localized exclusively in the grana thylakoids.

Comparison of Photosystem-I and Photosystem-II activities of spheroplasts from normal and photobleached Anabaena cylindrica

The analysis of photochemical activities of Photosystem I and Photosystem II in spheroplasts from normal and photobleached Anabaena cylindrica showed an increase in Photosystem II activity relative to Photosystem I in photobleached cells. We suggest that the reasons for this modification in photochemical activity are, (i) a rearrangement of pigments between the two photosystems, and (ii) improved functional condition of the photosynthetic units in Photosystem II.

Charakterisierung der PS I-Aktivität isolierter Chloroplasten aus Primärblättern von Triticum aestivum L. nach Temperaturbehandlung mit Hilfe der Entfärbung von Diphenylcarbazon (DPCN)

Summary The photochemical activity of photosystem I (PS I) of isolated wheat chloroplasts has been measured by means of the decolourization of diphenylcarbazone (DPCN) according to Shneyour and Avron (1971) and Vernon and Shaw (1972). Heating the chloroplast suspensions for 5 min up to 50 °C with following cooling results in a strong increase in the DPCN — decolourization, but treatment at 80 °C completely abolishes this reaction. At the same time the reduction of dichloro-phenolindophenol (DPIP) decreases in the usually described manner. It is discussed that the DPCN-decolourization may be representative for the activity only of a small part of the electron transport chain in the region of PS I, but it is very sensitive to variations in the native thylakoid structure.