Tuzhilkin Roman, Ondruška Vladimír, Šulc Miroslav
Department of Biochemistry, Faculty of Science, Charles University, Hlavova 2030, CZ-12843 Prague 2, Czech Republic.
Int J Mol Sci. 2025 Apr 26;26(9):4125. doi: 10.3390/ijms26094125.
Azurin is a small blue copper protein that participates in redox reactions during anaerobic respiration in , and there are a significant number of studies employing this model to investigate the electron transfer (ET) processes or coordination sphere of metal ion in metalloproteins. Azurin naturally contains Cu(II/I) as a central ion and is redox-active for a single electron ET. Moreover, azurin with no central ion (apo-azurin) is capable of binding other metal cofactors-e.g., Zn(II)-forming redox-inactive Zn-form and many others impacting the redox potential and structural variation in the active site's arrangement. Also, mutations of amino acid residues in the immediate vicinity of the metal ion can influence the structure and functionality of a particular metalloprotein. Therefore, this review aims to summarize the abundant information about selected topics related to redox reactions and blue copper proteins, particularly azurin, and is structured as follows: (i) introduction to the structure, properties, and physiological role of this group of metalloproteins, (ii) the role of the equatorial and axial ligands of the central metal ions, or metal species, in the active site on the metal coordination sphere's structure and related determination of the particular azurin form's redox potentials, and (iii) the effects of the particular amino acid's moiety (Phe, Tyr and Trp residues together with acceleration employing Trp-Trp π-π stacking interactions contrary to ET distance dependence) on the preferable type of long-range ET mechanism in an azurin-mediated model biomolecule. We assume that azurin is a suitable model to study the structural functionality of a particular central metal ion or individual amino acid residues in the central ion coordination sphere for studying the redox potential and ET reactions in metalloproteins.
天青蛋白是一种小型蓝色铜蛋白，参与[生物名称]厌氧呼吸过程中的氧化还原反应，并且有大量研究采用该模型来研究金属蛋白中金属离子的电子转移（ET）过程或配位球。天青蛋白天然含有Cu(II/I)作为中心离子，对单电子ET具有氧化还原活性。此外，不含中心离子的脱辅基天青蛋白（脱辅基蛋白）能够结合其他金属辅因子，例如Zn(II)，形成氧化还原无活性的锌形式以及许多其他影响活性位点排列中氧化还原电位和结构变化的物质。而且，金属离子紧邻区域的氨基酸残基突变会影响特定金属蛋白的结构和功能。因此，本综述旨在总结有关氧化还原反应和蓝色铜蛋白（特别是天青蛋白）相关选定主题的丰富信息，结构如下：(i) 介绍这组金属蛋白的结构、性质和生理作用；(ii) 中心金属离子或金属物种的赤道和轴向配体在活性位点对金属配位球结构的作用以及特定天青蛋白形式氧化还原电位的相关测定；(iii) 特定氨基酸部分（苯丙氨酸、酪氨酸和色氨酸残基，以及与ET距离依赖性相反的利用色氨酸 - 色氨酸π-π堆积相互作用的加速作用）对天青蛋白介导的模型生物分子中远程ET机制优选类型的影响。我们认为天青蛋白是研究金属蛋白中特定中心金属离子或中心离子配位球中单个氨基酸残基的结构功能以研究氧化还原电位和ET反应的合适模型。
