X-RAY STRUCTURAL STUDIES OF LACTOFERRIN

我们的主要目标是更好地理解 乳铁蛋白，牛奶中主要的铁结合蛋白， 其他身体分泌物和白细胞。 这将具有重要意义 对其他转铁蛋白和结合蛋白的一般意义。 该研究将解决金属离子和阴离子的结合和释放问题 通过乳铁蛋白，并将影响了解铁的控制 生物体液、身体防御机制（特别是抗- 细菌活性），人乳的生物学方面以及 微量元素的生物利用度。 它将建立在最近的解决办法， 人铁-乳铁蛋白（Fe_2 Lf）X射线结构 乳铁蛋白其它结构形式的晶体学分析 与相关蛋白质的比较，以及互补的光谱和 生化研究。 具体目标是： (I)完成人Fe 2 Lf的晶体学细化， 分辨率为2.2 A。 (II)人脱辅基乳铁蛋白的高分辨X射线结构分析， 形成最近获得的两种新的晶体形式。 其目的是定义 伴随铁结合和释放的构象变化。 (III)糖基化的结构效应（如有）研究 通过天然和去糖基化形式的比较结构研究， 乳铁蛋白 （四） 其他形式乳铁蛋白的结晶和结构分析， 包括单铁乳铁蛋白和乳铁蛋白片段。 （五） 乳铁蛋白的晶体学和光谱学比较 取代的其他金属和阴离子，包括结构的改进 铜乳铁蛋白 （六） 与其他转铁蛋白和细菌转铁蛋白的结构比较 结合蛋白，特别是来自沙门氏菌的SO 4 2-结合蛋白 鼠伤寒。 (VII)相关蛋白质（尤其是黑素转铁蛋白）的结晶 牛乳铁蛋白，用于随后的结构分析。 （八）作为一个长期目标， 乳铁蛋白的突变体。

Our broad aim is to better understand the molecular basis for the biological roles of lactoferrin, the major iron-binding protein in milk, other bodily secretion and leukocytes. This will have important implications for other transferrins and for binding proteins generally. The research will address the binding and release of metal ions and anions by lactoferrin, and will implications for understanding the control of iron levels in biological fluids, bodily defence mechanisms (especially anti- bacterial activity), aspects of the biology of human milk and the bioavailability of trace elements. It will build on the recent solution of the structure of human iron-lactoferrin, Fe2 Lf,through X-ray crystallographic analyses of other structural forms of lactoferrin comparisons with related proteins, and complementary spectroscopic and biochemical studies. Specific aims are: (I) Completion of the crystallographic refinement of the human Fe2 Lf, structures at 2.2 A resolution. (II) High resolution X-ray structure analyses of human apo-lactoferrin, form two new crystal forms recently obtained. These are aimed at defining the conformational changes accompanying iron binding and release. (III) Investigation of the structural effects (if any) of glycosylation through comparative structural studies of native and deglycosylated forms of lactoferrin. (IV) Crystallization and structure analyses of other forms of lactoferrin, including monoferric lactoferrin, and fragments of lactoferrin. (V) Crystallographic and spectroscopic comparisons of lactoferrin with other metals and anions substituted, including refinement of the structure of copperlactoferrin. (VI) Structural comparisons with other transferrins and with bacterial binding proteins, in particular the SO4 2- binding protein from Salmonella typhimurium. (VII) Crystallization of related proteins especially melanotransferrin and bovine lactoferrin, for subsequent structure analyses. (VIII) As a long-term aim, crystallographic studies on site-specific mutants of lactoferrin.