Oxygen Activation in Engineered Heme Proteins

加州理工学院化学系的Harry B. Gray博士和John H. Richards博士在化学系无机、生物无机和有机金属化学项目的支持下，开发了用于研究单血红素蛋白氧活化化学中的中间体的方法和材料。一系列的动力学研究，重点是关键的O-O键裂解反应将进行。将开发光化学方法，将电子快速注入血红素与铁配位的双氧中。根据目前的理论，这是在这些酶中引发O-O键断裂的步骤。通过对所得激发态的研究，可以得到反应中间体的信息和O-O键裂解机理的细节。待研究的系统包括血红素腔修饰形式的肌红蛋白、辣根过氧化物酶和酵母细胞色素c的突变体。氧气是一种强大且容易获得的氧化剂，但有效利用氧气的人造催化剂很少。氧活化和利用的最好例子是在生化系统中。含铁酶负责很大一部分生化氧活化。尽管如此，这些含铁生物分子激活氧气的确切方式尚不清楚。该项目旨在探索关键氧-氧键裂解过程的机制，这必须是该过程的核心。对生物系统如何运作的理解可能允许在各种实验室和工业过程中直接利用氧气的新方法。

Dr. Harry B. Gray and Dr. John H. Richards, Chemistry Department, California Institute of Technology, are supported by the Inorganic, Bioinorganic, and Organometallic Chemistry Program of the Chemistry Division to develop methods and materials for studying the intermediates in the oxygen-activation chemistry of single heme proteins. A series of kinetic studies which focus on the critical O-O bond cleavage reactions will be carried out. Photochemical methods will be developed for rapidly injecting electrons into the dioxygen coordinated to iron of a heme group. According to current theories is the step which initiates O-O bond cleavage in these enzymes. By study of the resulting excited states information will be obtained on reaction intermediates and the details of the O-O bond cleavage mechanism. Systems to be investigated include heme-cavity-modified forms of myoglobin, horseradish peroxidase, and mutants of yeast cytochrome c. Oxygen is a powerful and readily available oxidant, yet man-made catalysts that effectively utilize oxygen are rare. The best examples of oxygen activation and utilization are found in biochemical systems. Iron containing enzymes are responsible for a large portion of biochemical oxygen activation. Nonetheless, the exact way in which these iron containing biomolecules are able to activate oxygen is unclear. This project is designed to probe the mechanism of the critical oxygen-oxygen bond cleave process which must lie at the heart of the process. An understanding of how the biological systems operate may permit new ways of directly utilizing oxygen in a variety of laboratory and industrial processes.