ELECTRON-TRANSFER STUDIES OF COILED-COIL METALLOPROTEINS

描述：（逐字摘自申请人摘要）本提案旨在 研究生物电子转移（ET）反应的机制 通过合成和研究从头金属蛋白， α-螺旋卷曲螺旋的天然样结构。的重要特征 这些肽是它们提供了第一个明确定义的模型系统， 研究生物ET反应的机制，发生在一个 非共价肽-肽界面。它们也可以被衍生化来研究 沿着α-螺旋的共价骨架沿着发生的ET反应。30聚体 最近已经制备了一种多肽，并显示其自组装成 非共价双链α-螺旋卷曲螺旋。金属基氧化还原中心 (i.e. Ru（bpy）（trpy）Im-和Ru（NH3）5-）与组氨酸残基配位 位于两条肽链的每一条上的等同位置，以制备 电子转移金属蛋白，其特征在于， 分析方法。脉冲辐解被用来提供第一个 通过非共价键发生的电子转移反应的观察 在模型蛋白质中的肽-肽界面，k（et）= 9600 ± 700 s-1。的 本提案中描述的实验将进一步检查ET特性 阿尔法螺旋线圈将进行研究，以帮助确定如何， 或者如果非共价肽界面的各种化学改变可以 影响电子转移的速率。此外，亦会研究 发生在共价交联界面上的反应。最后，ET 将研究沿着单一共价骨架进行的反应， α-螺旋肽链。这项工作的未来结果应该提供 关于基于蛋白质的电子转移性质的有价值的信息 流程.

DESCRIPTION: (verbatim from applicant's abstract) This proposal seeks to investigate the mechanisms of biological electron-transfer (ET) reactions through the synthesis and study of de novo metalloproteins that have the native-like structure of an alpha-helical coiled-coil. An important feature of these peptides is that they provide the first well-defined model system in which to study the mechanisms of biological ET reactions that occur across a non-covalent peptide-peptide interface. They can also be derivatized to study ET reactions that occur along the covalent backbone of an alpha-helix. A 30-mer polypeptide has recently been prepared and shown to self-assemble into a non-covalent, two-stranded alpha-helical coiled-coil. Metal-based redox centers (i.e. Ru(bpy)(trpy)Im-, and Ru(NH3)5-) were coordinated to histidine residues located at equivalent positions on each of the two peptide chains to prepare the electron-transfer metalloprotein which has been characterized by a number of analytical methods. Pulse radiolysis was used to provide the first observation of an electron-transfer reaction occurring across a non-covalent peptide-peptide interface in a model protein with k(et) = 9600 +- 700 s-1. The experiments described in this proposal will further examine the ET properties of alpha-helical coiled-coils. Studies will be conducted to help determine how, or if, various chemical alterations of the non-covalent peptide interface can influence the rate of electron-transfer. Studies will also be conducted on reactions that occur across a covalently crosslinked interface. Finally, ET reactions will be studied that proceed along the covalent backbone of a single alpha-helical peptide chain. Future results from this work should provide valuable information about the nature of protein-based electron-transfer processes.