ELECTRON DENSITY MAPPING OF IRON PORPHYRINS

在过去十年中发展起来的精确的结晶学方法将是 在三维电子密度测绘中的应用 铁卟啉的分布。选定的化合物是 氧运输和电子转移血红蛋白的假体基团， 代表不同的氧化态、自旋态和配位 数字。除了增加我们对活跃分子的基础知识 血红蛋白的位置--实验电子密度分布 将回答一些具体的问题，这些问题涉及到 血红素电子结构的变化有助于协同作用 用于装卸氧气的机构。径向的差异 过渡金属电子分布与性质的依赖关系 将分析金属与配体之间的成键。了解以下内容 卟啉配体的电子结构将提供基本信息 它可以应用于更多的其他生物系统在 哪些卟啉络合物参与。实验电子密度 分配将服务于解释大量的 近几年收集的物理化学数据。这项研究将是 主要是在自动低温衍射设备上进行的 首席调查员实验室。将利用广泛的 本地开发的电荷密度分析程序库，由 衍射法。在以后的阶段中，部分测量将进行 SUNY光束线在国家同步加速器光源上的使用 布鲁克海文国家实验室将于1983年投入使用。

Accurate crystallographic methods developed over the last decade are to be applied in the mapping of the three dimensional electron density distribution of iron porphyrins. The compounds selected are models for the prosthetic group of oxygen-transport and electron-transfer hemoproteins, and represent different oxidation states spin states and coordination numbers. In addition to increasing our fundamental knowledge of the active site of the hemoproteins the experimental electron density distribution will answer a number of specific questions related to the extent to which changes in electronic structure of the heme contribute to the cooperativity mechanism for loading and unloading of oxygen. Differences in radial dependence of the transition metal electron distribution and the nature of the bonding between metal and ligands will be analyzed. Knowledge of the electronic structure of the porphyrin ligand will provide basic information which can be applied to the larger number of other biological systems in which porphyrin complexes participate. The experimental electron density distribution will serve in the interpretation of the large body of physico-chemical data collected in recent years. The research will be performed mainly on automated low temperature diffraction equipment in the principal investigators laboratory. Use will be made of an extensive library of locally developed programs for charge density analysis by diffraction methods. In a later stage part of the measurements will make use of the SUNY beamline at the National Synchrotron Light Source at Brookhaven National Laboratory which is to become operational during 1983.