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首页> 外文期刊>Dalton transactions: An international journal of inorganic chemistry >Active site structures and the redox properties of blue copper proteins: atomic resolution structure of azurin II and electronic structure calculations of azurin, plastocyanin and stellacyanin
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Active site structures and the redox properties of blue copper proteins: atomic resolution structure of azurin II and electronic structure calculations of azurin, plastocyanin and stellacyanin

机译：蓝铜蛋白的活性位点结构和氧化还原特性：Azurin II的原子拆分结构以及Azurin，质体蓝蛋白和恒星蓝蛋白的电子结构计算

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摘要

Understanding how the active site structures of blue copper proteins determine their redox properties is the central structure-function relationship question of this important class of protein, also referred to as cupredoxins. We here describe both experimental and computational studies of azurin, plastocyanin and stellacyanin designed to de. ne more accurately the geometric structures of the active site of the reduced and oxidized species, and thus to understand how these structures determine the redox potentials of these proteins. To this end the crystal structure of reduced azurin II has been determined at an atomic resolution of 1.13 angstrom and is presented here. Co-ordinates and structure factors have been deposited in the RCSB Protein Data Bank with accession codes 2ccw and r2ccwsf respectively. The improved accuracy provided by the atomic resolution for the metal stereochemistry are utilised in conjunction with the EXAFS data for theoretical calculations. Multilevel calculations involving density functional theory and molecular mechanical potentials are used to predict both the geometric and electronic structure of the active sites of azurin, plastocyanin and stellacyanin and to estimate the relative redox potentials of these three proteins. We have also compared the relative energies of the structures obtained from experiment at varying resolutions, and from the isolated and embedded cluster calculations. We find significant energy differences between low and high (atomic) resolution structures arising primarily due to inaccuracies in the Cu-ligand distances in the lower resolution structures, emphasising the importance of accurate, very high resolution structural information. QM/MM structures are only similar to 1 kcal mol(-1) lower in energy than the 1.13 angstrom structure while the optimized gas phase structure is 13.0 kcal mol(-1) lower in energy.
机译：理解蓝铜蛋白的活性位点结构如何决定其氧化还原特性是这一重要蛋白（也称为铜氧还蛋白）的核心结构-功能关系问题。我们在这里描述了旨在设计的天青素，质体蓝蛋白和硬脂蓝蛋白的实验和计算研究。可以更准确地了解还原和氧化物种的活性位点的几何结构，从而了解这些结构如何确定这些蛋白质的氧化还原电位。为此目的，已确定还原的天青蛋白II的晶体结构为1.13埃的原子分辨率，并在此给出。座标和结构因子已分别以2ccw和r2ccwsf的密码保存在RCSB蛋白质数据库中。原子分辨率为金属立体化学提供的提高的准确度与EXAFS数据一起用于理论计算。涉及密度泛函理论和分子机械势的多级计算被用于预测天青蛋白，质体蓝蛋白和恒星蓝蛋白的活性位点的几何和电子结构，并估计这三种蛋白的相对氧化还原势。我们还比较了以不同分辨率从实验以及隔离和嵌入式簇计算中获得的结构的相对能量。我们发现低分辨率和高分辨率（原子）结构之间存在明显的能量差异，这主要是由于低分辨率结构中Cu-配体距离的不准确所致，从而强调了准确，高分辨率的结构信息的重要性。 QM / MM结构的能量仅比1.13埃结构低1 kcal mol（-1），而优化的气相结构的能量低13.0 kcal mol（-1）。

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