TIME RESOLUTION OF STRUCTURE CHANGES IN METALLOENZYMES

酶和蛋白质中金属原子的性质和功能一直是 自Warburg在世界上首次发现以来，生物医学研究的重点 1930年S论“重金属酶催化”与凯林对 血球蛋白。研究这些重金属的许多生物物理方法 酶一直在进行中。光学和电子顺磁共振 研究是一个很好的例子，它给出了许多关于 属性，但有“盲点”未能提供关于 所有价或态的金属原子，即某些性质是“看不见的” 对大多数技巧来说。重金属原子对X射线的K边吸收发生在 所有的价态，并给出这些原子性质的明确指纹 以及它们的电子构型和化学环境。延伸边 吸收研究(EXAFF)提供了许多其他性质，其中一些可以 被解释为到重金属邻居的精确距离测量 原子。虽然相关数据最终可能是从x射线或核中推断出来的 根据磁共振数据，EXAFS方法的巨大潜在优势是 时间类金属蛋白结构研究的可能性 在具有酶功能的浓度下分解。光学和EPR样品 监测检测同步加速器下的价态或配基的任何变化 辐射。 该提案寻求建立仪器开发和测试 提高X-射线光子收集效率的组件 样品，最终目标是实现边缘吸收EXAFS和反常 在适当的酶活性研究范围内的分散研究，即较少 大于100微米M，最终向下延伸到微摩尔 浓度。伴随着这一发展而来的是基本的创新 酶中金属原子状态动力学研究的必要性 功能。最后但并非最不重要的是改进的在线样品监测方法 以确保生物材料在整个过程中的完整性 X射线照射。

The nature and function of metal atoms in enzymes and proteins has been a keystone of biomedical research since Warburg's initial discoveries in the 1930's on "heavy-metal enzyme catalysis" and Keilin's identification of hemoproteins. Many biophysical approaches to the study of these heavy metal enzymes have been in process. Optical and electron paramagnetic resonance studies are good examples of those that give definitive information on many properties but have "blind spots" that fail to give incisive information on the metal atoms in all valences or states, i.e., certain properties are "invisible" to most techniques. K edge absorption of X-rays by heavy metal atoms occurs in all valence states and gives definitive fingerprints of the nature of such atoms and their electronic configuration and chemical environment. Extended edge absorption studies (exafs) give many other properties, some of which can be interpreted as precise distance measurements to neighbors of the heavy metal atoms. While related data may ultmately be inferred from x-ray or nuclear magnetic resonance data, the great potential advantages of the exafs method are the possibilities of structural studies of the metalloproteins that are time resolved at enzymatically functional concentraions. Optical and epr sample monitoring detects any change of valence or liganding under synchrotron irradiation. This proposal seeks to set up instrumentation development and testing of components that increase the efficiency of photon collection from x-irradiated samples, the ultimate goal being to achieve edge absorption EXAFS and anomalous scattering studies in the range appropriate enzyme activity studies, i.e., less than 100 microns M and eventually extending down toward micromolar concentrations. Concomitant with this development are essential innovations necessary for kinetic studies of the state of mental atoms in enzymatic function. Last but not least are improved methods for on-line sample monitoring to ensure the integrity of the biological material throughout the course of the x-irradiation.