STRUCTURAL CHARACTERIZATION OF METAL TRANSPORTING PEPTIDES FROM MAMMALS & MICROO

该子项目是利用NIH/NCRR资助的中心赠款提供的资源的许多研究子项目之一。子项目和研究者（PI）可能从另一个NIH来源获得主要资金，因此可以在其他CRISP条目中表示。所列机构为中心，不一定是研究者所在机构。革兰氏阴性细菌中的铁摄取是通过使用铁载体（小的修饰肽）来完成的。铁载体从外部环境中吸收铁，然后被运输回细菌细胞。铁载体与有毒金属络合已被证明是一种有效的抗菌策略。我们将使用收集到的XAFS数据来关联金属结合性质和结构变化。我们还将使用金属结合位点的高分辨率XAFS数据来进一步改进我们的X射线晶体结构数据，这些数据将与这些实验并行解决。铁在人类的摄取正在研究的小肽，胃泌素17，其功能在胃腔在酸性pH值的胃泌素17已被证明结合两个铁原子，虽然没有结构数据尚未收集，证据表明，这些铁结合作为一个双核铁物种。XAFS数据不仅将提供铁结合位点的第一个结构图片，而且还可能提供金属相互结合程度的证据。最近有人推测，朊病毒蛋白，参与了一系列有害的神经系统疾病，可能作为一个铜感应或铜运输蛋白在哺乳动物的突触。铜结合已经与蛋白质的疾病状态的形成相关联，尽管原子分辨率结构数据很少。X射线晶体学几乎没有用处，因为铜结合区域在溶液中以及固态下是高度非结构化的。 此外，由于铜（Cu 2+）的顺磁性，NMR技术无法探测金属中心周围的区域。因此，我们正在筛选其他金属离子具有良好的NMR性能，使用XAFS技术与Cu 2+结合环境进行比较。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Iron uptake in gram negative bacteria is accomplished through the use of siderophores (small modified peptides). Siderophores scavenge iron from the external environment and are then transported back into the bacterial cell. Siderophores complexed to toxic metals have been shown to be an effective antibacterial strategy. We will use the collected XAFS data to relate metal-binding properties, and structural changes. We will also use the high resolution XAFS data of the metal-binding sites to further refine our X-ray crystal structure data, which will be solved in parallel with these experiments. Iron uptake in humans is being investigated by the small peptide, gastrin17, which functions in the gastric lumen at acidic pH. Gastrin17 has been shown to bind two Fe-atoms, and although no structural data has yet been collected, evidence suggests these irons are bound as a dinuclear iron species. XAFS data will not only provide the first structural picture of the iron-binding site, but may also provide evidence of how closely the metals are bound with respect to one another. It has recently been postulated that the prion protein, involved in a range of deleterious neurological diseases, may function as a copper-sensing or copper-transporting protein at the synapse in mammals. Copper-binding has been linked to the formation of the disease state of the protein, although atomic resolution structural data is sparse. X-ray crystallography is of little use as the copper-binding region is highly unstructured in solution, as well as the solid state. Also, due to the paramagnetic nature of copper (Cu2+) NMR techniques are unable to probe the region immediately around the metal centre. We are therefore screening other metal ions with favourable NMR properties, using the XAFS technique to compare with the Cu2+-binding environment.