Molecular Models for H2-Activating Metalloenzymes

该奖项在无机，生物无机和有机化学 该计划支持Marcetta Darensbourg博士对金属酶的研究 德克萨斯农工大学化学系教授 的重点 研究的是（NiFe）氢化酶的反应化学， 促进二氢的形成、固定和感应。 的 脱硫弧菌氢化酶的活性位点是异双核的 (Fe、Ni），而铁中心似乎与氰基有关， 羰基。 在这项工作中，已知的有机金属阴离子 CpFe（CN）2（CO），其中Fe = Fe（I），Fe（II）将研究它们的能力 信号电子密度的变化，在Cp取代基引起的 氢键或溶剂相互作用。 振动光谱学将 用于监测伴随氧化还原的电子密度变化， 酶活性水平。 此外，新设计的二硫代磷酸酯配体 将用于将镍络合物配位到铁单元， 作为酶的结构模型。 关于的假设 催化过程是铁单元提供稳定 通过一个吸电子的铁网站，介导的电荷通过 硫醇盐，从而易于接近催化活性Ni（I）;或 二氢生产催化涉及Fe（II）位点， 二硫醇镍作为双齿配体， 可通过氧化还原状态或连接的变化来调节。 氢化酶具有重要的生物学功能， 为细胞提供能量。 已经发现这些酶含有两种金属， 铁和镍，在活性反应位点，但这些金属如何 在反应中的合作是未知的。 过去的许多研究 研究了镍的作用，但这项研究将阐明 铁和铁镍化合物的作用。 结果还可能 与混合金属工业催化剂的功能有关， 功能还不太清楚。

This award in the Inorganic, Bioinorganic, and Organometallic Chemistry Program supports research on metalloenzymes by Dr. Marcetta Darensbourg of the Chemistry Department, Texas A&M University. The focus of the investigation is the reaction chemistry of (NiFe)hydrogenase, an enzyme that promotes the formation, fixation, and sensing of dihydrogen. The active site of the Desulfovibrio gigas hydrogenase is heterobinuclear (Fe, Ni) and the iron center appears to be associated with cyano and carbonyl groups. In this work, the known organometallic anions CpFe(CN)2(CO) where Fe = Fe(I), Fe(II) will be studied for their ability to signal electron density changes at Cp substitutents caused by hydrogen-bonding or solvent interaction. Vibrational spectroscopy will be used to monitor the electron density changes accompanying redox and enzyme activity levels. In addition, newly designed dithiolate ligands will be used to coordinate nickel complexes to the iron unit which may serve as a structural model for the enzyme. The hypothesis concerning the catalysis process is that either the iron unit provides stabilization via an electron-withdrawing iron site that mediates charge through the thiolates, thus easing accessibility to catalytically active Ni(I); or the dihydrogen production catalysis involves the Fe(II) site, with the nickel dithiolate serving as a bidentate ligand that is electronically tunable by changes in redox state or ligation. Hydrogenase enzymes perform important biological functions that provide energy to cells. These enzymes have been found to contain two metals, iron and nickel, at the active reaction site, but how these metals cooperate in the reaction is unknown. Many past studies have investigated the role of nickel, but this research will elucidate the role of iron, and of the iron-nickel combination. The results may also be relevant to the functioning of mixed metal industrial catalysts whose functioning is not well understood.