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一个重要的研究课题。 自瓦尔堡在1989年的首次发现以来， 20世纪30年代关于"重金属酶催化"和Keilin的鉴定 血红素蛋白 研究这些重金属的许多生物物理方法 酶在过程中。 光学和电子顺磁共振 研究是很好的例子，这些研究提供了许多 属性，但有"盲点"，未能提供精辟的信息， 所有价态或状态的金属原子，即，某些属性是"不可见的" 大多数技术。 重金属原子对X射线的K边吸收发生在 所有的价态，并给出了这些原子的性质的明确的指纹 以及它们的电子构型和化学环境。 延伸边缘 吸收研究（exafs）给出了许多其他性质，其中一些可以 被解释为与重金属的邻居的精确距离测量 原子的 虽然相关的数据可能最终从x射线或核推断出来， 磁共振数据，exafs方法的巨大潜在优势是 金属蛋白结构研究的可能性， 在酶功能浓度下解析。 光学和epr样品 在同步加速器下，监测可检测化合价或配位的任何变化 辐照 该提案旨在建立仪器开发和测试， 提高从X射线照射的光子收集效率的部件 样品，最终目标是实现边缘吸收EXAFS和异常 在适当的酶活性研究范围内的散射研究，即，少 超过100微米M，并最终向下延伸到微摩尔 浓度的 与这种发展相伴随的是重要的创新 酶促反应中金属原子状态的动力学研究 功能 最后但并非最不重要的是在线样品监测的改进方法 为了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.