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首页> 外文期刊>Biochemistry >Binding and Energetics of Electron Transfer between an Artificial Four-Helix Mn-Protein and Reaction Centers from Rhodobacter sphaeroides
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Binding and Energetics of Electron Transfer between an Artificial Four-Helix Mn-Protein and Reaction Centers from Rhodobacter sphaeroides

机译：从脱乳氏菌的人工四螺母Mn-蛋白和反应中心之间的电子转移的结合和能量学。

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摘要

The ability of an artificial four-helix bundle Mn-protein, P1, to bind and transfer an electron to photosynthetic reaction centers from the purple bacterium Rhodobacter sphaeroides was characterized using optical spectroscopy. Upon illumination of reaction centers, an electron is transferred from P, the bacteriochlorophyll dimer, to QA, the primary electron acceptor. The P1 Mn-protein can bind to the reaction center and reduce the oxidized bacteriochlorophyll dimer, P+, with a dissociation constant of 1.2 μM at pH 9.4, comparable to the binding constant of c-type cytochromes. Amino acid substitutions of surface residues on the Mn-protein resulted in increases in the dissociation constant to 8.3 μM. The extent of reduction of P+ by the P1 Mn-protein was dependent on the P/P+ midpoint potential and the pH. Analysis of the free energy difference yielded a midpoint potential of approximately 635 mV at pH 9.4 for the Mn cofactor of the P1 Mn-protein, a value similar to those found for other Mn cofactors in proteins. The linear dependence of ?56 mV/pH is consistent with one proton being released upon Mn oxidation, allowing the complex to maintain overall charge neutrality. These outcomes demonstrate the feasibility of designing four-helix bundles and other artificial metalloproteins to bind and transfer electrons to bacterial reaction centers and establish the usefulness of this system as a platform for designing sites to bind novel metal cofactors capable of performing complex oxidation–reduction reactions.]]>
机译：<！[cdata [ src ='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/bichaw/2017/bichaw.2017.56.issue-49/acs.biochem.7b00978/ 20171206 /图像/中/ Bi-2017-00978P_0011.gif“>人工四螺旋束Mn-蛋白，P1的能力从紫色细菌中与光合反应中心结合和转移电子，乳菌氏菌病/ i>使用光学光谱表征。在反应中心照射时，将电子从p，菌氯苯二聚体转移到q a ，初级电子受体。 P1 Mn-蛋白可以与反应中心结合并减少氧化的菌氯基丙二聚体P + ，在pH 9.4下的解离常数为1.2μm，与 c的结合常数相当。 / i> -type细胞学。在Mn-蛋白上的表面残留氨基酸取代导致解离常数增加至8.3μm。 P1 MN-蛋白的P + / sup>还原的程度取决于p / p + 中点电位和pH。对自由能量的分析在p1mN-蛋白的Mn辅因子的pH 9.4下产生约635mV的中点电位，其值类似于蛋白质中的其他Mn辅因子的值。 α56mV/ pH的线性依赖性与在Mn氧化时释放的一个质子一致，允许复合物保持总电荷中立。这些结果证明了设计四螺旋束和其他人造金属蛋白的可行性，以将电子与细菌反应中心结合和转移，并建立该系统的有用性作为设计能够进行复杂氧化还原反应的新型金属辅因子的部位的平台。]]>

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  • 来源
    《Biochemistry》 |2017年第49期|共10页
  • 作者

    Eduardo Espiritu; Tien L. Olson; JoAnn C. Williams; James P. Allen;

  • 作者单位

    School of Molecular Sciences Arizona State University Tempe Arizona 85287-1604 United States;

    School of Molecular Sciences Arizona State University Tempe Arizona 85287-1604 United States;

    School of Molecular Sciences Arizona State University Tempe Arizona 85287-1604 United States;

    School of Molecular Sciences Arizona State University Tempe Arizona 85287-1604 United States;

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  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 生物化学;
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