当前位置: X-MOL 学术J. Biol. Inorg. Chem. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Effective binding of Tb 3+ and La 3+ cations on the donor side of Mn-depleted photosystem II
JBIC Journal of Biological Inorganic Chemistry ( IF 2.7 ) Pub Date : 2020-11-04 , DOI: 10.1007/s00775-020-01832-w
Elena R Lovyagina 1 , Aleksey V Loktyushkin 1 , Boris K Semin 1
Affiliation  

The interaction of Tb3+ and La3+ cations with different photosystem II (PSII) membranes (intact PSII, Ca-depleted PSII (PSII[-Ca]) and Mn-depleted PSII (PSII[-Mn]) membranes) was studied. Although both lanthanide cations (Ln3+) interact only with Ca2+-binding site of oxygen-evolving complex (OEC) in PSII and PSII(-Ca) membranes, we found that in PSII(-Mn) membranes both Ln3+ ions tightly bind to another site localized on the oxidizing side of PSII. Binding of Ln3+ cations to this site is not protected by Ca2+ and is accompanied by very effective inhibition of Mn2+ oxidation at the high-affinity (HA) Mn-binding site ([Mn2+ + H2O2] couple was used as a donor of electrons). The values of the constant for inhibition of electron transport Ki are equal to 2.10 ± 0.03 µM for Tb3+ and 8.3 ± 0.4 µM for La3+, whereas OEC inhibition constant in the native PSII membranes is 323 ± 7 µM for Tb3+. The value of Ki for Tb3+ corresponds to Ki for Mn2+ cations in the reaction of diphenylcarbazide oxidation via HA site (1.5 µM) presented in the literature. Our results suggest that Ln3+ cations bind to the HA Mn-binding site in PSII(-Mn) membranes like Mn2+ or Fe2+ cations. Taking into account the fact that Mn2+ and Fe2+ cations bind to the HA site as trivalent cations after light-induced oxidation and the fact that Mn cation bound to the HA site (Mn4) is also in trivalent state, we can suggest that valency may be important for the interaction of Ln3+ with the HA site.



中文翻译:

Tb 3+ 和La 3+ 阳离子在Mn耗尽光系统II的供体侧的有效结合

研究了 Tb 3+和 La 3+阳离子与不同光系统 II (PSII) 膜(完整的 PSII、Ca 耗尽的 PSII (PSII[-Ca]) 和 Mn 耗尽的 PSII (PSII[-Mn]) 膜)的相互作用. 尽管两种镧系元素阳离子 (Ln 3+ ) 仅与PSII 和 PSII(-Ca) 膜中的释氧复合物 (OEC) 的Ca 2+结合位点相互作用,但我们发现在 PSII(-Mn) 膜中,Ln 3+离子与位于 PSII 氧化侧的另一个位点紧密结合。LN的结合3+阳离子的网站不受保护的Ca 2+和伴随的Mn非常有效的抑制2+在高亲和力(HA)的Mn结合位点的氧化([锰2+ + H 2 O 2 ] 对用作电子供体)。电子传递K i抑制常数的值对于 Tb 3+等于 2.10 ± 0.03 µM,对于 La 3+为 8.3 ± 0.4 µM ,而天然 PSII 膜中的 OEC 抑制常数对于 Tb 3为 323 ± 7 µM +。的值ķ为TB 3+相当于ķ为锰2+在经由HA的网站上的二苯卡巴肼氧化反应的阳离子(1.5μM)呈现在文献中。我们的结果表明 Ln 3+阳离子与 PSII(-Mn) 膜中的 HA Mn 结合位点结合,如 Mn 2+或 Fe 2+阳离子。考虑到 Mn 2+和 Fe 2+阳离子在光诱导氧化后作为三价阳离子结合到 HA 位点以及结合到 HA 位点 (Mn4) 的 Mn 阳离子也处于三价状态,我们可以建议该价态对于 Ln 3+与 HA 位点的相互作用可能很重要。

更新日期:2020-11-04
down
wechat
bug