EPR AND ENDOR STUDIES OF PROTEIN DI-IRON-OXO CLUSTERS

过渡金属离子存在于许多 蛋白质对于生命的基本过程至关重要， 呼吸和复制。 蛋白质的关键作用 双核铁氧簇在这些过程中正在建立 随着这些金属蛋白的发现越来越多。 的目的 这项建议是应用和开发新的方法，可以探测 蛋白质的活性位点，从而提供有关起源的信息 二铁氧蛋白所表现出的功能多样性。 直到最近，金属蛋白的EPR研究一直局限于那些 显示半整数自旋（S = 1/2，3/2，...），但最近的事态发展 保证了这项技术更广泛的适用性。 具体而言是 被忽略的具有整数自旋的金属蛋白（S = 1，2，.）现在可以 研究EPR。 本文将整数自旋EPR应用于 光谱来表征的双氧活性铁簇的 二铁氧蛋白 此外，活性位点的结构方面 (iron连接、底物效应和可及性）进行测定 从靠近铁的原子核的超精细耦合的大小。 用ENDOR光谱测量超精细耦合。 几 以前的ENDOR研究二铁氧簇存在，因此工作 这里提出的将建立一个坚实的基础，解释ENDOR 这些类型的金属簇的光谱。

The transition-metal ions that are found in the active centers of many proteins are essential for fundamental processes of life such as respiration and replication. The pivotal role that proteins containing dinuclear iron-oxo clusters have in these processes is being established as more occurrences of these metalloproteins are discovered. The aim of this proposal is to apply and develop new methods that can probe the active sites of proteins, and thus give information concerning the origin of the functional diversity exhibited by diiron-oxo proteins. Until recently, EPR studies of metalloproteins have been limited to those exhibiting half-integer spin (S = 1/2, 3/2, ...), but recent developments promise much wider applicability of the technique. Specifically, the neglected metalloproteins with integer spin (S = 1, 2, ...) can now be studied with EPR. The study proposed here will apply integer spin EPR spectroscopy to characterize the dioxygen active iron clusters of diiron-oxo proteins. In addition, structural aspects of the active sites (iron ligation, substrate effects and accessibility) will be determined from the magnitudes of hyperfine couplings of nuclei close to the irons. The hyperfine couplings are measured with ENDOR spectroscopy. Few previous ENDOR studies of diiron-oxo clusters exist, thus the work proposed here will establish a firm basis for the interpretation of ENDOR spectra of these types of metal clusters.