Understanding coupled transfers of electrons and protons relevant to biological c

其中一个质子和一个电子在一个动力学步骤中转移。这样的过程被称为协调一致 质子-电子转移(CPET)是更大的质子耦合电子转移(PCET)领域的一个子集。 这些过程在生物学的许多领域都是基本的，从使用氧化还原反应到产生 生物能源学中的质子梯度，对有机自由基的产生和反应。 其中一组具体目标集中在氢原子转移过程上，这涉及到协调一致 电子和质子从施主到受主的转移。这样的反应是至关重要的，例如，在 捕捉活性氧物种(由维生素E、抗坏血酸、超氧化物歧化酶等)，因此 与老化和其他过程有关。氢原子转移裂解C-H键是关键步骤 在许多金属酶的催化循环中，包括细胞色素P450，各种非血红素铁 加氧酶和依赖维生素B12的酶。我们的论证表明，一系列氢原子 转移反应遵循马库斯理论提供了一个框架，以建立对这些过程的理解。 第二组具体目标集中在分离的CPET反应上，在该反应中，电子和质子 转到不同的组。它们可能参与许多生物氧化还原反应，例如， 光系统II和细胞色素C氧化酶对分子氧的形成和还原。最好的 所研究的例子是光系统II中Tyrosyl-Z自由基的形成；这个过程的模型是 建议。 一些拟议的研究将模拟重要生物过程中的具体步骤，如苯二酚 线粒体BC^复合体中Rieske铁-硫簇的氧化。其他研究的目的是 探索一般原理，而不是具体的生物系统。例如，建议进行的研究 苯酚基化合物的氧化将探索骨架运动如何影响氢转移，这是一个问题 目前关于酶催化起源的争论很多。 对基本化学反应的理解是生物学和生物科学发展的基础 医药。有关电子转移反应的详细知识已被证明在 生物化学。拟议的研究正在建立对CPET反应的类似理解：通过 从广泛的角度来看，通过检查一些不同的系统和一组不同的反应，这 工作是揭示支配不同类别的电子和电子的耦合转移的原理 质子。

which one proton and one electron transfer in a single kinetic step. Such processes, termed concerted proton-electron transfer (CPET), are a subset of the larger field of proton-coupled electron transfer (PCET). These processes are fundamental in many areas of biology, from the use of redox reactions to generate proton gradients in bioenergentics, to the generation and reactivity of organic radicals. One set of specific aims are focused on hydrogen atom transfer processes, which involve concerted transfer of an electron and a proton from a donor to an acceptor. Such reactions are critical, for example, in the trapping of reactive oxygen species (by vitamin E, ascorbate, superoxide dismutase, etc.), and are thus related to aging and other processes. The cleavage of C-H bonds by hydrogen atom transfer is a key step in the catalytic cycles of many metalloenzymes, including cytochrome P450, various non-heme iron oxygenases, and vitamin B12-dependent enzymes. Our demonstration that a range of hydrogen atom transfer reactions follow Marcus theory provides a framework to build an understanding of such processes. A second set of specific aims are focused on separated CPET reactions, in which the electron and proton transfer to different groups. These are likely to be involved in many biological redox reactions, for instance, the formation and reduction of molecular oxygen by photosystem II, and cytochrome c oxidase. The best studied example is the formation of the tyrosyl-Z radical in photosystem II; models for this process are proposed. Some of the proposed studies will model specific steps in important biological processes, such as quinone oxidation by the Rieske iron-sulfur cluster in the mitochondrial bc^ complex. Other studies are designed to probe general principles rather than specific biological systems. For example, the proposed studies of oxidation of phenol-base compounds will probe how framework motions affect hydrogen transfers, an issue of much current debate regarding the origins of enzymatic catalysis. An understanding of fundamental chemical reactions underlies many kinds of developments in biology and medicine. The detailed knowledge available for electron transfer reactions has proven to be of great value in biological chemistry. The proposed studies are building a similar understanding for CPET reactions: by taking a broad perspective, by examining a number of different systems and a diverse set of reactions, this work is uncovering the principles that govern the different classes of coupled transfers of electrons and protons.