ELECTRON-TRANSFER STUDIES OF COILED-COIL METALLOPROTEINS

描述：(逐字摘自申请人的摘要)这项提案旨在 研究生物电子转移(ET)反应的机理 通过对新型金属蛋白的合成和研究 阿尔法螺旋螺旋线圈的原生结构。的一个重要特点 这些多肽是它们提供了第一个定义明确的模型系统 来研究生物ET反应的机制，这些反应发生在 非共价肽-多肽界面。它们也可以被派生出来研究 沿着α-螺旋的共价骨架发生的ET反应。30岁以下 最近制备的多肽被证明可以自组装成一种 非共价型，双股α-螺旋盘状线圈。金属基氧化还原中心 (即Ru(Bpy)(Trpy)Im-和Ru(NH3)5-)与组氨酸残基配位 位于两条多肽链上的相同位置以制备 电子转移金属蛋白已经被表征了许多 分析方法。脉冲辐解用于提供第一个 发生在非共价键上的电子转移反应的观察 模型蛋白质中的多肽-多肽界面，k(Et)=9600-700 S-1。这个 本提案中描述的实验将进一步检查ET的属性 阿尔法螺旋盘绕的线圈。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变化可以 影响电子转移的速度。此外，我们亦会就以下事项进行研究 发生在共价交联界面上的反应。最后，ET 将研究沿着单个共价骨架进行的反应 α-螺旋多肽链。这项工作的未来结果应该会提供 关于蛋白质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.