[Comparative study of the oxygen reduction in photosystem II of the cyanobacteria, Anacystis nidulans and Anabaena variabilis].

Oxygen reduction in the photosystem II (PS II) of thylakoid membranes from the cyanobacteria Anacystis nidulans and Anabaena variabilis was studied in the system SiMo + DCMU in whose presence competitive electron transport to SiMo and O2 in possible. The reagents of the Mehler reaction were used; these reagents activate oxygen uptake by interacting with the reduced forms of oxygen (malonate and oxalate with O2; glyoxylate and catalase + ethanol with H2O2). The use of the reagents as shown that there was a considerable electron transport to O2 which decreased the rate of SiMo reduction and visible oxygen evolution.

[Studies of oxygen uptake (Mehler reactions) in chloroplasts in the presence of silico-molybdic acid].

Silico-molybdic acid (SiMo) alone or in combination with diurone is known to provide for the functioning of various sites of electron transport within photosystem II (PS-II). Using SiMo, the ability of PS-II to competitive reduction of O2 with SiMo in the presence of some activators of O2 uptake (e. g.

[Localization of the Meler's reaction with ethanol catalase trap in the chain of photosynthetic electron transport].

The common view of photosystem I as the action site of catalase and ethanol at oxygen uptake in chloroplasts are based on indirect data on this reaction. That is why the question on Mehler reaction localization in electron transport chain with ethanolcatalase trap has been investigated anew. It has been demonstrated that oxygen uptake with catalase and ethanol does not decrease in presence of dibromothymoquinone (2,5-dibromo-3-methyl-6 isopropyl-p-benzoquinone--DBTQ) which blocks electron transfer to photosystem I at plastoquinones level.