Spectroscopic and Computational Mapping of Biological and Biomimetic Hydrogenase Mechanisms

CBET-0755676 Szilagyi拟议的研究直接解决了催化和生物催化计划的目标，通过定义生物制氢和利用的分子基础，为非化石二氢生产提供突破的潜力。我们将开发FeFe氢化酶和相关的结构和/或功能类似模型的定量结构和活性关系（QSAR）。我们将使用光谱校准的计算工具，在生物氢代谢的势能面上定位中间体和过渡态。拟开发的虚拟分子模型将定义氢吸收和释放过程的分子机制。我们将影响合理化的设计和优化的新型化合物，模仿的FeFe氢化酶（H-簇）的有效活性位点。研究方法的一个独特方面是实验技术（多边缘X射线吸收近边缘结构，XANES和扩展X射线精细结构，EXAFS分析）和理论方法（多层密度泛函/分子轨道/分子力学计算，DFT/MO/MM）的创新整合。我们的组合光谱（在lumeno）和计算（在硅片）的方法，结果在现代密度泛函理论的光谱校准是必不可少的，以增加在硅片模型预测催化功能的可靠性。具体来说，我们的目标是-了解的作用和重要性的生物独特的，有机金属配体环境的H-簇，作为一个最有效的，非贵金属为基础的催化剂，氢的演变和利用，通过定义的基本电子结构特性，确定的H-簇？消除了XANES和EXAFS对绿色衣藻FeFe氢化酶的铁氧化态、羰基与氰化物配位、二硫代硫酸盐辅因子的组成、活性中心簇内电子连接的不确定性;- 通过采用DFT/MO/H2O，为10-15 μ m的H-簇和附属铁-硫簇的环境开发现实的计算机模型。MM整合了用于绘制氢释放和吸收势能面的理论，并剖析了蛋白质环境如何调节导致高催化活性的各种位点的结构、氧化还原电位和质子化。除了发现高度优化的氢化酶活性位点的结构，稳定性和反应性的基本物理化学性质外，我们的生物物理和计算方法的发展很可能会影响其他含铁硫金属酶的研究。PI在计算化学和X射线吸收光谱学方面的专业知识以及合作者的背景为科学发现和学生培训创造了多学科的研究环境。PI的学生将从合作者那里学习样品制备的细节;相反，PI将在XAS光束线上接待合作者的学生。PI致力于对本科生和研究生进行计算化学和光谱学培训。他维护一个最新的网站，以有效地传播他的研究，教学和软件/硬件工程活动。

CBET-0755676SzilagyiThe proposed research directly addresses the objectives of the Catalysis and Biocatalysis program by defining the molecular basis of biological hydrogen production and utilization with potentials for providing breakthroughs in non-fossil dihydrogen production. We will develop quantitative structure and activity relationships (QSAR) for FeFe-hydrogenases and related structurally and/or functionally analogous models. We will locate the intermediates and transition states on the potential energy surface of the biological hydrogen metabolism using spectroscopically calibrated computational tools. The virtual molecular models to be developed will define the molecular mechanisms of the hydrogen uptake and evolution processes. We will impact the rationalized design and optimization of novel compounds that mimic the efficient active site of the FeFe-hydrogenases (H-cluster). A unique aspect of the research approach is the innovative integration of experimental techniques (multi-edge X-ray absorption near-edge structure, XANES, and Extended X-ray fine structure, EXAFS, analyses) and theoretical methods (multi-layered density functional/molecular orbital/molecular mechanical computations, DFT/MO/MM). Our combined spectroscopic (in lumeno) and computational (in silico) approach that results in the spectroscopic calibration of modern density functional theory are essential for increasing the reliability of in silico models in predicting catalytic function. Specifically, we aim to - understand the role and importance of the biologically unique, organometallic ligand environment of the H-cluster, as one of the most efficient, non-noble metal-based catalysts for hydrogen evolution and utilization, by defining the fundamental electronic structure properties that determine the H-cluster?s stability and catalytic activity; - eliminate the uncertainties in iron oxidation states, carbonyl vs. cyanide coordination, composition of the dithiolate cofactor, electronic connection within the active site clusters of FeFe-hydrogenases from green alga Chlamydomonas reinhardtii by XANES and EXAFS; - develop realistic in silico models for a 10-15 Å environment of the H-cluster and the accessory iron-sulfur clusters by employing DFT/MO/MM integrated theory for mapping the potential energy surface of hydrogen evolution and uptake, and dissecting how the protein environment tunes the structure, redox potential, and protonation of various sites that leads to the high catalytic activity. In addition to the discovery of fundamental physico-chemical properties of structure, stability, and reactivity of the highly optimized hydrogenase active site, our biophysical and computational method development will very likely influence research into other iron-sulfur containing metalloenzymes. The PI's expertise in computational chemistry and X-ray absorption spectroscopy and the collaborators' backgrounds create a multidisciplinary research environment for scientific discovery and student training. The PI's students will learn the fine details of sample preparations from collaborators; conversely, the PI will host the collaborators' students at the XAS beamlines. The PI is committed to training undergraduate and graduate students in computational chemistry and spectroscopy. He maintains an up-to-date website for efficiently disseminating his research, teaching, and software/hardware engineering activities.