X-RAY STRUCTURAL STUDIES OF LACTOFERRIN

我们的广泛目标是更好地了解 乳铁蛋白是牛奶中主要的铁结合蛋白， 其他体液和白细胞。这将具有重要的意义 对其他转铁蛋白和一般结合蛋白的影响。 这项研究将研究金属离子和阴离子的结合和释放 乳铁蛋白，以及威尔对理解铁的控制的意义 生物液中的水平，身体防御机制(特别是抗- 细菌活性)、母乳生物学方面以及 微量元素的生物可利用性。它将建立在最近的解决方案 人乳铁蛋白Fe2Lf的X射线结构 乳铁蛋白其他结构形式的结晶学分析 与相关蛋白质的比较，以及互补光谱和 生化研究。具体目标是： (I)完成人类Fe2Lf的结晶提纯， 结构，分辨率为2.2A。 (Ii)人脱脂乳铁蛋白的高分辨X射线结构分析， 形成最近获得的两种新的晶型。这些都是为了定义 伴随着铁结合和释放的构象变化。 (3)研究糖基化的结构效应(如果有的话) 通过对天然形式和脱糖形式的比较结构研究 乳铁蛋白。 (4)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。 (V)乳铁蛋白与乳铁蛋白的结晶学和光谱比较 其他金属和阴离子被取代，包括结构的精炼 含铜乳铁蛋白。 (Vi)与其他转铁蛋白和细菌的结构比较 结合蛋白，特别是沙门氏菌的SO42结合蛋白 鼠伤寒杆菌。 (Vii)相关蛋白质的结晶，特别是黑素转铁蛋白和 牛乳铁蛋白，用于后续结构分析。 (八)作为一项长期目标，对特定地点进行结晶学研究 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.