Conformations of c-type cytochrome self-assembling complexes

描述（由申请人提供）：电子转移（ET）反应对于包括光合作用和呼吸作用在内的广泛的生物学重要过程至关重要。在光合作用和呼吸作用中，ET反应需要有组织的蛋白质组装。我们的长期目标是确定蛋白质构象在ET中的作用。这需要构建和研究能够进行ET的模型超分子组装。我们的假设是c型细胞色素将提供这样一个模型系统。我们的假设基于三个观察：(1)它们参与几乎所有生物体的呼吸过程，(2)有些可以自组装成链，(3)当它们与某些小分子结合时，它们能够转移电子。多结构域c-细胞色素作为元件应用于仿生储能装置，如电线或催化位点。关于这些超分子结构的详细结构信息将有助于深入了解构象在ET反应中的作用及其作为ET制剂的适用性。为了在生物环境（水溶液）中解析这些配合物的结构，采用了广角x射线散射技术。然而，这种技术需要构建分子模型来解释实验数据。因此，这项工作的具体目标是使用分子动力学来创建这样的模型，计算它们的x射线散射模式，并通过与实验数据的比较，提供c型细胞色素复合物的原子水平图像。在本中试项目中，我们将：(1)通过液相分子动力学计算和计算与实验散射数据的比较，建立构象模型，阐明细胞色素c7的二、三、四聚体的结构；(2)收集足够的资料，以便提交sc1类型的建议书。这项工作的成功完成将阐明构象在ET中的作用以及细胞色素c7复合物作为能量存储装置的构建块的适用性。

DESCRIPTION (provided by applicant): Electron transfer (ET) reactions are crucial for a wide range of biologically important processes including photosynthesis and respiration. In photosynthesis and respiration, ET reactions require an organized assembly of proteins. Our long-term goal is to determine the role of protein conformation on ET. This requires the construction and investigation of model supramolecular assemblies capable of ET. Our hypothesis is that c-type cytochromes will provide such a model system. We base this hypothesis on three observations: (1) they are involved in the respiratory processes of almost all organisms, (2) some can self-assemble into chains, and (3) they are capable of electron transfer when bound to certain small molecules. Multi-domain c-cytochromes have applications as components in bio-mimetic energy storage devices as electric wires or catalytic sites. Detailed structural information about these supramolecular architectures would provide insight into the role of conformation in ET reactions and their suitability as ET agents. To resolve the structure of these complexes in their biological environment (aqueous solutions) wide-angle X-ray scattering techniques are employed. However, this technique requires the construction of molecular models to interpret the experimental data. Hence, the specific goal of the proposed work is to use molecular dynamics to create such models, calculate their X-ray scattering patterns, and by comparison to the experimental data, provide an atomic level picture of c-type cytochrome complexes. In this pilot project, we will: (1) elucidate the structure of di-, tri-, and tetramers of cytochrome c7 by construction of conformation models via solution phase molecular dynamics calculations and comparison of the calculated and experimental scattering data; (2) acquire sufficient data to allow submission of a SC1-type proposal. Successful completion of this work will illuminate the role of conformation in ET and the suitability of cytochrome c7 complexes as building blocks for energy storage devices. Relevance to Public Health: The current study focuses on evaluating a self-assembling system that has been proposed as a new solar energy storage device. More efficient solar energy systems would allow a reduction in fossil fuel usage which, due to its contribution to air pollution, has been linked to increasing respiratory disorders.