X-RAY STRUCTURES OF RICIN, ABRIN, BOWMAN-BIRK INHIBITORS

本研究的主要目标是了解 蓖麻毒蛋白OR、相思豆毒蛋白A和相思豆毒蛋白C的毒性及结构特征 鲍曼-伯克型蛋白酶抑制剂。 PI-I、PI-II和PI-V。 这些蛋白质已经结晶到最佳大小， 晶体学研究 它们的晶体厚度至少为3埃 蓖麻毒素OR的分辨率为3埃，相思豆毒素C的分辨率为3埃，相思豆毒素A的分辨率为6埃， 1.8 PI-I为2.5埃，PI-II为2.5埃， 对于毒性凝集素（蓖麻毒素OR、相思豆毒素A和C），我们将确定 它们的结构，研究A链和B链之间的关系， 比较蓖麻毒素OR和蓖麻毒素D之间的结构细节，以及 蓖麻毒素和相思豆毒素，并分析这些大分子如何能够穿透 细胞膜 这一信息对我们至关重要 了解这些蛋白质的毒性机制， 有助于设计用于靶特异性细胞破坏的混合毒素。 细胞特异性毒素的潜在用途有很多，例如在 “toxosurgery”的癌细胞，去除淋巴细胞的某些 接受组织移植等的特异性。 Bowman-Birk型抑制剂，我们将确定它们的结构， 该抑制剂家族内的结构以及与其他家族。 由于鲍曼-伯克家族代表了一种独特的蛋白质结构类型 这种类型的详细架构以前没有 说明，知识将获得从这项研究不仅 将增加我们对结构-功能关系的理解， 蛋白酶抑制剂，而且还将扩大我们对基本的 蛋白质的折叠模式。 本研究的第二个目标是测试和改进迭代 单同构置换与迭代单反常 散射方法，PI。用于X射线分析 大分子。 我们将把这些新技术应用于 确定所提出的蛋白质结构。 我们的研究将 提高对如何最佳使用这些技术的理解， 哪里需要改进。

The primary goal of this research is to understand the structural basis for the toxicity of ricin OR, abrin A and abrin C, and the structural features in the bowman-Birk, type proteinase inhibitors. PI-I, PI-II and PI-V. These proteins have been crystallized to the optimal sizes for crystallographic studies. Their crystals diffract to at least 3 angstroms resolution for ricin OR, 3 angstroms for abrin C, 6 angstrom for abrin A, 1.8 angstroms for PI-I, 2.5 angstroms for PI-II and 2.5 angstroms for PI-V. For the toxic lectins (ricin OR, abrin A and C) we will determine their structures, study the relationships between the A and B-chains, compare the structural details between ricin OR and ricin D, and between ricin and abrin, and analyze how these macromolecules can penetrate the cell membrane. This information will be of vital importance to our understanding of the mechanism of toxicity in these proteins, and for aiding the design of hybrid toxins for target- specific cell destruction. The potential use of cell specific toxins are many, for example in the "toxosurgery" of cancer cells, the removal of lymphocytes of certain specificity for the acceptance of a tissue transplant, etc. For the Bowman-Birk type inhibitors we will determine their structures, compare the structures within this inhibitor family as well as with other families. Since the Bowman-Birk family represents a unique type of protein structure and the detailed architecture of this type has not been previously illustrated, the knowledge which will be gained from this research not only will increase our understanding on the structure-function relationship of proteinase inhibitors but also will widen our perspective on the basic folding patterns of proteins in general. The secondary goal of this research is to test and refine the iterative single isomorphous replacement and the iterative single anomalous scattering methods that the P.I. has recently developed for X-ray analysis of macromolecules. We will apply these new techniques to the determinations of the proposed protein structures. Our studies will increase the understanding of how to use these techniques optimally and where to make needed improvement.