ELECTRON DENSITY MAPPING OF HEMOGLOBIN MODEL COMPOUNDS

精确的晶体学方法被用来绘制 血红蛋白模型化合物的电子分布 自旋态、价态和配位数的函数。 的 研究将集中在小分子（NO，CO，O2） 卟啉和钴席夫碱的加合物，以阐明 电子性质的金属加合物键合，这是必不可少的，我们 了解氧气吸收机制。 另外还 将导出从金属到配体的电荷转移量， 金属配体相互作用的共价性和非球面性 金属原子的电荷分布。 该信息 有望填补我们现有知识的重要空白， 回答一些具体问题， 血红素电子结构的变化 氧气装卸的协同机制。 这些结果将有助于我们了解大量的 涉及血红素蛋白的生物学过程。 实验数据也将在常规X射线上收集 作为同步辐射源。 特别是，在 CHESS，康奈尔高能同步加速器源，将被使用 以获得液氦温度下的数据。 增加的 分辨率可在低波长结合非常低 温度构成了实验的重大改进 方法.

Accurate crystallographic methods are being used to map the electron distribution of hemoglobin model compounds as a function of spin state, valency and coordination number. The research is to be focussed on small molecule (NO, CO, O2) adducts of porphyrins and cobalt Schiff bases to elucidate the electron nature of metal-adduct bonding which is essential for our understanding of the oxygen uptake mechanism. Specifically we will derive the amount of charge transfer from metal to ligand, the covalency of the metal ligand interaction and the asphericity of the metal atom charge distribution. This information is expected to fill important gaps in our present knowledge and 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. The results will aid in our understanding of the large number of biological processes involving heme proteins. Experimental data will be collected on conventional X-ray as well as synchrotron sources. In particular, the wiggler beamline at CHESS, the Cornell High Energy Synchrotron Source, will be used to obtain data at liquid helium temperature. The increased resolution available at low wavelenghts combined with very low temperatures constitute a major improvement in experimental methods.