Understanding coupled transfers of electrons and protons relevant to biological c

其中一个质子和一个电子在单个动力学步骤中转移。这种进程，称为协调一致的进程， 质子-电子转移（CPET）是质子耦合电子转移（PCET）的更大领域的子集。 这些过程是生物学许多领域的基础，从使用氧化还原反应生成 生物能学中的质子梯度，有机自由基的产生和反应性。 一组具体的目标是集中在氢原子转移过程，其中涉及协调 电子和质子从供体转移到受体。这些反应是关键的，例如， 活性氧的捕获（通过维生素E、抗坏血酸盐、超氧化物歧化酶等），并且因此 与衰老和其他过程有关。通过氢原子转移裂解C-H键是一个关键步骤 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 加氧酶和维生素B12依赖酶。我们证明了一系列氢原子 转移反应遵循马库斯理论提供了一个框架，以建立这样的过程的理解。 第二组具体目标集中在分离的CPET反应，其中电子和质子 转移到不同的群体。它们可能参与许多生物氧化还原反应，例如， 通过光系统II和细胞色素c氧化酶形成和还原分子氧。最好的 研究的例子是在光系统II中形成酪氨酰-Z自由基;该过程的模型是 提出了 一些拟议的研究将模拟重要生物过程中的特定步骤，如醌 氧化的Rieske铁硫簇在线粒体bc^复合物。其他研究旨在 探索一般原理，而不是特定的生物系统。例如，拟议的研究 酚基化合物的氧化将探索框架运动如何影响氢转移， 关于酶催化的起源的争论。 对基本化学反应的理解是生物学许多发展的基础， 药电子转移反应的详细知识已被证明是非常有价值的， 生物化学拟议的研究正在建立对CPET反应的类似理解： 采取广泛的观点，通过检查一些不同的系统和各种反应， 工作是揭示支配不同类别的电子耦合转移的原理， 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.