RESONANCE SPECTROSCOPY OF METALLOPROTEINS

我们建议研究的电子和分子结构的 金属蛋白中的活性中心主要利用磁性 共振和穆斯堡尔谱。 我们的主要兴趣集中在 与O2-H2O-H2 O2氧化还原反应相互作用的铁蛋白 系统 最终目标是阐明结构和动态 控制反应路径的特征。 研究将 沿着几条线前进。 (i)我们会调查 导致细胞色素P450 CAM中的双氧活化， 特别强调复杂的形成之间的 单加氧酶和2Fe-2S rdox/效应蛋白， putidaredoxin。 EPR/ENDOR参数的比较 分离的蛋白质与双分子复合物的蛋白质应 揭示自旋-自旋相互作用和/或构象的影响 变化 为了支持分配，putidaredoxin的同源性 利用已知的藻类铁氧还蛋白结构， H2O/D2 O中的ENDOR。 (ii)将尝试诱捕一只 电子，通过低温辐解，在血红素-O2复合物上 底物结合的oxyP 450 CAM。 将使用EPR和ENDOR 以探测预期的血红素-O2自由基及其反应 产品退火。 (iii)为了跟进观察到的一个 脱氧肌红蛋白中的EPR信号（21），我们将探索其他S=2 血红素和非血红素铁蛋白中的状态用于这种信号。 的 能级和跃迁几率将由自旋 具有参数分布的哈密顿量。 单晶和 高频电子顺磁共振，以及穆斯堡尔光谱，将是 用来进一步了解能级的分布 在这些系统中。 (iv)与当地的化学家合作， 在其他大学，我们将继续我们的EPR和Mossbauser 过氧化物酶中高氧化态中间体的研究 和过氧化氢酶和自旋耦合的双核簇在 血红蛋白和紫色酸性磷酸酶。 模型系统将 分析与金属蛋白比较，如果它们承诺 更多的见解。

We propose to study the electronic and molecular structure of active centers in metalloproteins using primarily magnetic resonance and Mossbauer spectroscopy. Our main interest focuses on iron proteins that interact with the O2-H2O-H2O2 redox system. The ultimate goal is to elucidate structural and dynamic features that control the reaction pathways. Research will proceed along several lines. (i) We will investigate the events leading to dioxygen activation in cytochrome P450CAM, with specific emphasis on complex formation between the monooxygenase and the 2Fe-2S rdox/effector protein, putidaredoxin. Comparisons of EPR/ENDOR parameters of the isolated proteins with those of the bimolecular complex should reveal effects of spin-spin interactions and/or conformational changes. To support assignments, the homology of putidaredoxin with the known structure of algal ferredoxin will be examined by ENDOR in H2O/D2O. (ii) Attempts will be made to trap an electron, by low temperature radiolysis, on the heme-O2 complex of substrate-bound oxyP450CAM. EPR and ENDOR will be used to probe for the expected heme-O2 radical and its reaction products on annealing. (iii) To follow up on the observation of an EPR signal in deoxymyoglobin (21) we will explore other S=2 states in heme and non-heme iron proteins for such signals. The energy levels and transition probabilities will be modeled by a spin Hamiltonian with a distribution of parameters. Single-crystal and high-frequency EPR, as well as Mossbauer spectroscopy, will be used to gain further insight into the distribution of energy levels in these systems. (iv) In collaboration with chemists locally and at other universities we will continue our EPR and Mossbauser studies of higher oxidation state intermediates in the peroxidases and catalases and of the spin-coupled binuclear clusters in hemerythrin and purple acid phosphatase. Model systems will be analyzed for comparison with metalloproteins if they promise further insights.