EPR and Mossbauer Characterization of Mn and Fe Proteins, Models, Intermediates

说明(申请人提供)：锰、蛋白质和酶在多种生物学功能中都很重要。锰在人体内的相对含量和分布是已知的，然而，由于锰的结合力相对较弱，锰影响人类健康的机制现在才刚刚开始解开。锰在真核生物和原核生物的许多细胞过程中都起着重要的作用。这两种单核锰酶(双加氧酶和丙酮羧基酶)由于其独特的底物激活机制，将在本提案中被研究。此外，金属运输和监管系统是一个日益增长的研究领域。最近，一种锰转运调节蛋白(MntR)的结构被表征为具有双核的锰结合位点。我们将研究MntR中锰中心的光谱特征，以及它如何识别DNA对锰的响应。在解释单核和双核锰中心的EPR谱方面取得了根本性的进展，这将使定量表征蛋白质和酶的活性锰中心具有前所未有的能力。这将应用于上述蛋白质，也将用于双核锰酶噬菌体lambda-磷酸酶的鉴定。通过对仿生复合体的研究，将深入了解锰和铁酶激活氧和氮的机制。检测和表征这类机制中的中间产物对于理解该机制至关重要。两种不同的仿生复合体及其氧或氮衍生中间体将被表征。

DESCRIPTION (provided by applicant): Manganese proteins and enzymes are important in a diverse range of biological functions. The relative amounts and distribution of Mn in humans is known, however, due to the relatively weak binding of Mn, the mechanisms by which Mn can affect human health are only now beginning to be unraveled. Manganese plays an essential role in many cellular processes of both eukaryotes and prokaryotes. Two mononuclear Mn enzymes (Dioxygenase and Acetone Carboxylase) will be investigated in this proposal due to their unique mechanisms of substrate activation. In addition, metal transport and regulation systems are a growing area of study. Recently, a Mn transport regulatory protein (MntR) has been structurally characterized to show a dinuclear Mn site. A spectroscopic characterization of the Mn centers in MntR and how it recognizes DNA in response to Mn will be investigated. A fundamental advance in the interpretation of EPR spectra for both mono- and dinuclear Mn centers will allow an unprecedented ability to quantitatively characterize the active Mn sites of proteins and enzymes. This will be applied to the above proteins, and also for a characterization of the dinuclear Mn enzyme Bacteriophage lambda-Phosphatase. Insight into the mechanism of oxygen and nitrogen activation by Mn and Fe enzymes will be derived from studies of biomimetic complexes. The detection and characterization of intermediates in such mechanisms is critical for an understanding of the mechanism. Two different families of biomimetic complexes and their oxygen or nitrogen derived intermediates will be characterized.