Probing the Electronic Structure of Fe-S Clusters

描述(申请人提供)：ALL中存在铁硫蛋白 生物物质，是自然界中分布最广的蛋白质之一。 它们构成了一类重要的生物电子转移剂，但 越来越多地被发现具有更多的生物功能。它们的功能 在很大程度上取决于其活性中心的电子结构 蛋白质环境施加的影响。最活跃的站点 通常由一个铁中心组成，铁(2)S(2)，铁(3)S(4)和铁(4)S(4) 簇，通常由半胱氨酸侧链上的硫配位 周围的蛋白质。大自然进化了一系列不同的功能， 只有为数不多的铁-S通过微调蛋白质环境形成簇。它 因此对于理解Fe-S团簇的性质和 对其周围环境的修改，以了解它们的性质和 铁硫蛋白的功能。然而，Fe-S团簇是 极其复杂的电子系统。这项提议旨在试验性地 Fe-S在气相中的电子结构和性质 以它们的裸体、模拟复合体和蛋白质的形式聚集在一起。毒气 相研究不受溶剂或晶体的干扰 场，得到了Fe-S团簇的内禀性质，并允许 蛋白质环境的影响有待直接探测。实验性的 这项提案中的方法是非常规的，利用了最近 生物质谱学和气相光谱学的研究进展 技巧。将使用电喷雾离子源来传输Fe-S团簇 和蛋白质进入气相。Fe-S团簇的负电荷离子 和蛋白质将被光分离光电子询问 光谱学，产生关于它们的电子结构的直接信息 分子内的静电相互作用。因为照片分离是 类似于氧化过程，拟议的实验也将产生 Fe-S团簇氧化还原反应的能量信息。它是 预计拟议工作的新实验结果将 促进理论的进一步进步。

DESCRIPTION (provided by applicant): Iron-sulfur proteins are present in all living matter and represent one of the most distributed proteins in nature. They constitute a class of important biological electron transfer agents, but are increasingly found to have more biological functions. Their functionality is critically dependent on the electronic structure of their active sites and the influences imposed by the protein environment. The active sites most frequently consist of a one-Fe center, Fe(2)S(2), Fe(3)S(4), and Fe(4)S(4) clusters, usually coordinated by sulfur from the cysteine side chains of the surrounding proteins. Nature has evolved a diverse range of functionality with just the few Fe-S clusters through fine-tuning of the protein environment. It is thus crucial to understand the properties of the Fe-S clusters and modifications by their surroundings in order to understand the properties and functionalities of the iron-sulfur proteins. However, Fe-S clusters are extremely complicated electronic systems. This proposal seeks to experimentally probe, in the gas phase, the electronic structure and properties of the Fe-S clusters in their bare forms, in analog complexes, and in proteins. The gas phase investigations are free from the perturbation of solvents or crystal field, yields the intrinsic properties of the Fe-S clusters, and allows the influences of the protein environments to be probed directly. The experimental approaches in this proposal are unconventional, taking advantages of recent developments in biological mass spectrometry and gas-phase spectroscopic techniques. An electrospray ion source will be used to transport Fe-S clusters and proteins into the gas phase. Negatively charged ions of the Fe-S clusters and proteins will be interrogated by photodetachment photo-electron spectroscopy, which yields direct information about their electronic structures and intramolecular electrostatic interactions. Because photodetachment is analogous to an oxidation process, the proposed experiments will also yield energetic information relevant to redox reactions of Fe-S clusters. It is expected that the new experimental results from the proposed work will stimulate further theoretical advancements.