Mass Spectrometric Analysis of N2-Formation Induced by the Oxidation of Hydrazine and Hydroxylamine in Flash Illuminated Thylakoid Preparations of the Filamentous Cyanobacterium Oscillatoria chalybea

P. He*, K. P. Bader, and G. H. Schmid Universität Bielefeld, Fakultät für Biologie, Lehrstuhl Zellphysiologie, D-4800 Bielefeld 1, Bundesrepublik Deutschland Z. Naturforsch. 46c, 629-634 (1991); received March 21, 1991 Filamentous Cyanobacterium, Photosystem II, Water Splitting, S-States, Hydrogen-Peroxide Analogue In tobacco chloroplasts hydrazine-dependent dinitrogen formation measured by mass spec­ trometry as the consequence o f short saturating light flashes is always linked to a substantial oxygen uptake (G. Renger, K. P. Bader, and G. H. Schmid, Biochim. Biophys. Acta 1015, 288, 1990). However, in thylakoids o f the filamentous cyanobacterium Oscillatoria chalybea this dinitrogen formation is not linked to an apparent 0 2-uptake, even at the high concentration of 1 m M hydrazine. Whereas in tobacco chloroplasts Tris-treatment does not affect hydrazine de­ pendent dinitrogen formation up to a concentration o f 3 m M hydrazine, Tris-treatment o f thy­ lakoids o f O. chalybea affects strongly both oxygen evolution and dinitrogen evolution under a single turnover flash as well as under ten flashes. In contrast to tobacco chloroplasts, the pres­ ence o f hydrazine up to concentrations o f 3 m M does not substantially affect photosynthetic 0-,-evolution. The observed dinitrogen evolution is affected by DCM U regardless whether in­ duced by a single turnover flash or by ten flashes, whereas in tobacco dinitrogen evolution and the 0-,-uptake linked to it (which is not observed in the cyanobacterium) were clearly not af­ fected by DCM U in the single turnover flash. In Oscillatoria the earlier described Photosystem II-mediated H-,0-, formation and decomposition is influenced by hydrazine. In the presence of 300 hm hydrazine the usually present 0 2-uptake leading to H:0 : formation appears dimin­ ished.