Mechanism of Inhibition of the Oxygen-Evolving Complex of Photosystem II by Lanthanide Cationsстатья
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Дата последнего поиска статьи во внешних источниках: 15 февраля 2024 г.
Аннотация:Abstract—The interaction of La3+ and Tb3+ cations with the Ca-binding site of the oxygen-evolving complexof photosystem II samples depleted of calcium has been studied. The binding of cations to the Ca-binding siteis irreversible and the bound cations cannot be washed out or replaced by Ca2+ cations. The feature of lanthanidesto bind strongly to the Ca-binding site was used to investigate whether the bound Ln3+ cation has aneffect on the high-affinity Mn-binding site of the oxygen-evolving complex. For this purpose, hydroquinonewas used to extract manganese cations from the oxygen-evolving complex of the calcium-depleted photosystemII membranes with the Ca-binding site blocked by La3+ or Tb3+, and the activity of the high-affinity sitewas then examined using exogenous electron donors (Mn2+ + H2O2) and 1,5-diphenylcarbazide. It wasfound that lanthanide cations bound to the Ca-binding site significantly inhibited oxidation of electrondonors through the high-affinity Mn-binding site. The mechanism of the observed effect is discussed.