Thermoluminescence evidence for light‐induced oxidation of tyrosine and histidine residues in manganese‐depleted photosystem II particles

[摘要]

In the thermoluminescence (TL) glow curve of photosystem II, particles depleted of manganese, a tyrosine modifier, 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD) a bolishes the TL band appearing around −55°C (TL₋₅₅). Addition of a histidine modifier, diethylpyrocarbonate results in the disappearance of the band peaking around −30°C (TL₋₃₀). NBD treatment also abolishes the EPR signal II_fast of oxidized tyrosine donor, Y₂₁ and inhibits the electron transport from diphenylcarbazide to 2,6-dichlorophenol-indophenol. It is concluded that the TL₋₅₅ and TL₋₃₀ bands can be assigned to oxidized tyrosine (Y₂ ⁺) and histidine (His⁺) residues, respectively, which participate in electron transfer from manganese to the reaction center of chlorophyll, P680⁺.

[学科分类] 生物化学/生物物理

[关键词] Histidine;Tyrosine;Photosystem II;Electron transport;Manganese-depletion;Thermoluminescence;DCPIP;2;2-dichlorophenol-indophenol;DEPC;die-thylpyrocarbonate;DPC;diphenylcarbazide;DT-20;oxygen evolving photosystem II particle;FeCy;ferricyanide;His+;redox active histidine residue;NBD;7-chloro-4-nitrobenz-2-oxa-1;3-diazole;QA;primary quinone acceptor of photosystem II;SiMo;silicomolybdate;PS II;photosystem II;Yz +;tyrosine;donor of PS II