Oxygen evolution by photosystem II membranes was inhibited by Cu(II) when 2,6-dichlorobenzoquinone or ferricyanide, but not silicomolybdate, was used as electron acceptor. This indicated that Cu(II) affected the reducing side of the photosystem II. The inhibition curves of Cu(II), o-phenanthroline and 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU), were compared; the inhibitory patterns of Cu(I...

Iron is an essential component in many protein complexes involved in photosynthesis, but environmental iron availability is often low as oxidized forms of iron are insoluble in water. To adjust to low environmental iron levels, cyanobacteria undergo numerous changes to balance their iron budget and mitigate the physiological effects of iron depletion. We investigated changes in key protein abun...

This chapter describes the purification and crystallization of oxygen-evolving photosystem II core dimer complex from a thermophilic cyanobacterium Thermosynechococcus vulcanus. Procedures used for purification of photosystem II from the cyanobacterium involves cultivation of cells, isolation of thylakoid membranes, purification of crude and pure photosystem II core complexes by detergent solub...

Chloroplast structure and function is known to alter during foliar senescence. Besides, the alterations in the structural organisation of thylakoid membranes changes in the steady state levels of thylakoid membrane proteins occur due to leaf ageing. We monitored temporal changes in some of the specific proteins of thylakoid membrane protein complexes by western blotting in the Cucumis sativus c...

1. CO2-depletion of thylakoid membranes results in a decrease of binding affinity of the Photosystem II (PS II) inhibitor atrazine. The inhibitory efficiency of atrazine, expressed as I50-concentration (50% inhibition) of 2,6-dichlorophenolindophenol reduction, is the same in CO2-depleted as well as in control thylakoids. This shows that CO2-depletion results in a complete inactivation of a par...

The potential of measurements of chlorophyll fluorescence in vivo to detect cellular responses to salinity and degrees of salt stress in leaves was investigated for three crop plants. Sugar beet (Beta vulgaris L.) (salt tolerant), sunflower (Helianthus annuus L.) (moderately salt tolerant), and bean (Phaseolus Vulgaris L. cv Canadian Wonder) (salt intolerant) were grown in pots and watered with...

Bala Krishna Kolli, Swati Tiwari and Prasanna Mohanty School of Life Sciences, Jawaharlal Nehru University, New Delhi 110 067, India Z. Naturforsch. 53c, 369-377 (1998); received December 15, 1997 Fluorescence Transients, Photosystem II, Quinones, Spirulina, Ultraviolet-B When Spirulina platensis filaments were exposed to 0.75 mW.m_2.s_1 of ultraviolet-B radi­ ation (the ultraviolet-B radiation...

A third group o f antibiotics, the aurachins, have been isolated from the m yxobacterium Stigmatella aurantiaca. The aurachins chemically are quinolones, and four o f them (aurachins A D ) have been tested for their inhibitory activity in photosystem II and cytochrom e b/ccomplexes. A urachin C is the best inhibitor in photosystem II (p /50-value 7.2); its biochemical behaviour being the same l...

Chloroplasts isolated from pea seadlings grown on water containing 45Ca2+ were treated with local anesthetic tetracaine. Addition of tetracaine inactivated the electron transport activity of donor side photosystem II. This inhibition was accompanied by 45Ca2+ release from the chloroplast membranes as the whole and destroyed by osmotic shock. No such effect was observed when Tris or hydroxylamin...