VIBRATIONAL STUDIES OF METAL CLUSTERS IN PROTEINS

锰是生物体中一种必不可少的微量元素 氧气的各种氧化还原转化。一个新的计划将是 开发以探索结构和反应性的基本问题 用光谱学方法研究生物体系的锰活性中心 方法，特别是共振拉曼(RR)光谱。初始目标 将包括超氧化物歧化酶(SODS)的单核锰(III)位点 和双核非血红素锰过氧化氢酶，有几个看似合理的 已经提出了一些结构。我们的方法将是获得 蛋白质和精选模型的高质量RR谱 络合物，借助低温拉曼技术和可变 激发波长，并记录尽可能多的频率和同位素 尽可能多地换班。然后将执行正常模式计算， 基于结构特征的锰仿生模型系统，利用 目标是开发物理上可信的力场，能够 准确地再现观测到的频率和同位素位移 详细了解被监测的振动模式的性质。 RR和溶液FT-IR光谱将用于阐明 超氧化物单核金属中心上的阴离子相互作用模式 通过探测铜、锌、铁和铁的配体振动来研究歧化酶 含锰超氧化物歧化叠氮加合物。精氨酸残留(Arg)的影响 141)叠氮化物上的化学改性和磷酸盐加成 振动频率将被用来提供对 Arg 141在SOD催化过程中的表达。对……本质的理解 正在监测的振动模式将允许锁定结构 这些重要酶的特性，并建立蛋白质结构 与它们的活性金属位置的化学相关的变化。

Manganese is an essential trace element in living organisms to perform various redox transformations of dioxygen. A new program will be developed to explore fundamental questions of structure and reactivity at manganese active sites of biological systems by using spectroscopic methods, particularly resonance Raman (RR) spectroscopy. Initial targets will include the mononuclear Mn(III) site of superoxide dismutases(SODs) and dinuclear non-heme Mn-catalases for which several plausible structures have been proposed. Our approach will be to obtain high-quality RR spectra of proteins and of judiciously chosen model complexes, with the aid of low-temperature Raman techniques and variable excitation wavelengths, and to record as many frequencies and isotope shifts as possible. Normal mode calculations will then be carried out, based on structurally characterized Mn biomimetic model systems, with the aim of developing physically plausible force fields capable of reproducing the observed frequencies and isotope shifts accurately and to understand in detail the nature of vibrational modes being monitored. The RR and solution FT-IR spectroscopies will be used to elucidate the anion interaction modes at the mononuclear metal sites of superoxide dismutases by probing ligand vibrations of the Cu,Zn-, Fe-, and Mn-containing SOD-azide adducts. The effects of arginine residue (Arg 141) chemical modification and phosphate addition on azide-bound vibrational frequencies will be used to provide insights into the role of Arg 141 in the SOD catalytic process. An understanding of the nature of the vibrational modes being monitored will allow to pin down structural features of these important enzymes, and to establish protein structural changes associated with the chemistry of their active metal sites.