Tribromotoluquinone Induced Modifications of the Oscillation Pattern of Oxygen Evolution and of Herbicide Binding in Thylakoids and PS II Membrane Fragments from Spinach

摘要: In the present study effect of TBTQ on PS II and its mutual interaction with DCMU was analyzed by measurements oxygen yield oscillation pattern binding. It found: 1)TBTQ in reduced form is able to induce reduction Dᵒˣ which gives rise an accelerated decay S₂ S₃ wateroxidizing complex. 2) Triton X-100 treatment used for isolation membrane fragments does not significantly affect lateral mobility p lastoquinone within membrane. bound thylakoid enhance electron pool capacity fragments. 3) Preincubation thylakoids diminishes blockage O2-evolution significantly. correspondence previous findings [18, 19] strongly depends order addition . 4) Excitation a single saturating flash causes enhanced binding pretreated samples leading inhibition induced evolution. The rate latter process concentration. 5) d ark 3rd slowly declines as function o f dark incubation time at constant Based above mentioned it inferred that between takes place acceptor side. Two alternative mechanisms are discussed: i) tightly (covalently?) QB-site (or very close it) modified via structural effects (allosteric type), or ii) there occurs /DCMU exchange fast light slow dark.