Probing the Electronic Structure of Fe-S Clusters

描述（由申请人提供）：铁硫蛋白存在于所有 是自然界中分布最广的蛋白质之一。 它们构成一类重要的生物电子转移剂，但 越来越多的人发现它们具有更多的生物学功能。其功能性 关键取决于其活性位点的电子结构， 蛋白质环境的影响。最活跃的网站 通常由单Fe中心、Fe（2）S（2）、Fe（3）S（4）和Fe（4）S（4）组成。 簇，通常由来自半胱氨酸侧链的硫配位， 周围的蛋白质大自然已经进化出各种各样的功能， 通过对蛋白质环境的微调，它 因此，对于理解Fe-S团簇的性质至关重要， 为了理解其属性， 铁硫蛋白的功能。然而，Fe-S簇是 极其复杂的电子系统该提案旨在通过实验 探讨了气相中Fe-S体系的电子结构和性质 在它们裸露的形式，在模拟复合物，和在蛋白质中的簇。气体 相研究不受溶剂或晶体的干扰 场，产生Fe-S团簇的固有性质，并允许 直接探测蛋白质环境的影响。实验 该提案中的方法是非常规的，利用了最近的 生物质谱和气相光谱的发展 技术.电喷雾离子源将被用来传输Fe-S团簇 和蛋白质进入气相。Fe-S团簇的负电荷离子 蛋白质将通过光分离光电子 光谱，它产生有关其电子结构的直接信息 和分子内静电相互作用。因为光剥离 类似于氧化过程，所提出的实验也将产生 与Fe-S团簇氧化还原反应有关的能量信息。是 预计新的实验结果，从拟议的工作将 推动理论进一步发展。

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.