X RAY STRUCTURAL STUDIES OF LACTOFERRIN

描述（改编自申请人的摘要）：乳铁蛋白是一种突出的 来自人乳、其他分泌物和白细胞的铁结合蛋白， 具有多种已确定或拟议的生物活性。 它也与密切相关的血清蛋白转铁蛋白，部分的 一组调节铁水平的蛋白质，可能还有其他 金属，在动物的体液中。 这项研究的主要目的是 (i)以确定人类生物活性的分子基础， 乳铁蛋白，（ii）解决更广泛的铁稳态问题， 将这些结构-功能研究扩展到血清转铁蛋白，以及（iii） 研究这些蛋白质特异性的结构基础。 它 将对理解铁水平的控制产生影响， 体液中的其他微量元素，与铁相关的疾病 超负荷或缺乏;身体防御机制，特别是抗菌 和抗氧化活性;人乳和婴儿生物学方面 健康和微量元素的生物利用度。 这项研究将使用X射线晶体学的补充技术 和定点诱变来确定决定金属和 阴离子结合亲和力和结合和释放机制，并探测 通过转铁蛋白结合和运输的多功能性。 这是一个合乎逻辑的 我们以前对乳铁蛋白的晶体学研究的扩展， 新开发的转铁蛋白结构工作;结构知识将 用于选择诱变的靶标，并且突变蛋白将被 通过X射线晶体学和溶液研究表达和表征。 具体目标是：1。 利用诱变和晶体学来分析 铁位点后的碱性残留物对铁的影响 release. 2. 分析铁配体和阴离子结合的作用 基团决定金属阴离子的亲和力和特异性。 3. 到 用X射线确定转铁蛋白协同性的结构基础 分析具有不同构象状态和不同 两个脑叶中的铁含量。 4. 探讨乳铁蛋白的作用 通过结晶和X射线结构分析， 乳铁蛋白-DNA复合物。 5. 研究装订的多功能性 通过转铁蛋白，通过与Ru（III）抗肿瘤的络合物的结晶 据报道，转铁蛋白携带的药物，并通过X射线分析， 一种新的转铁蛋白，它结合一种强有力的有机毒素代替铁。 6. 为了完成糖基化对结构的影响的研究， 转铁蛋白的功能。

DESCRIPTION (Adapted from applicant's abstract): Lactoferrin is a prominent iron-binding protein from human milk, other secretions, and leukocytes and possesses a wide variety of established or proposed biological activities. It is also, with the closely-related serum protein transferrin, part of the team of proteins that regulates the levels of iron, and possibly other metals, in the body fluids of animals. The broad aims of this research are (i) to determine the molecular basis for the biological activities of human lactoferrin, (ii) to address the wider questions of iron homeostasis by extending these structure-function studies to serum transferrin, and (iii) to investigate the structural basis of specificity in these proteins. It will have implications for understanding the control of levels of iron and other trace elements in body fluids, with relevance to diseases of iron overload or deficiency; bodily defense mechanism, especially antibacterial and antioxidant activity; aspects of the biology of human milk and infant health, and the bioavailability of trace elements. The research will use the complementary techniques of x-ray crystallography and site-directed mutagenesis to define the factors that determine metal and anion binding affinity and mechanisms of binding and release, and to probe the versatility of binding and transport by transferrins. It is a logical extension of our previous crystallographic studies of lactoferrin and newly-developed structural work on transferrin; structural knowledge will be used to select targets for mutagenesis and the mutant proteins will be expressed and characterized by x-ray crystallography and solution studies. Specific aims are: 1. To use mutagenesis and crystallography to analyze the importance of basic residues behind the iron site in influencing iron release. 2. To analyze the roles of the iron ligands and anion binding groups in determining metal an anion affinity and specificity. 3. To determine the structural basis of cooperativity in transferrins by x-ray analysis of molecules with different conformational states and different iron status in the two lobes. 4. To probe the proposed role of lactoferrin as a transcription factor by crystallization and x-ray structural analysis of lactoferrin-DNA complexes. 5. To investigate the versatility of binding by transferrins, by crystallization of complexes with Ru(III) anti-tumor drugs that are reportedly carried by transferrins, and by x-ray analysis of a novel transferrin that binds a potent organic toxin in place of iron. 6. To complete a study of the effects of glycosylation on the structure and function of transferrin.