Oxygen Activation in Engineered Heme Proteins

加州理工学院化学系哈里·B·格雷博士和约翰·H·理查兹博士在化学部无机化学、生物无机化学和金属有机化学计划的支持下，开发研究单一血红素蛋白氧活化化学中间体的方法和材料。将进行一系列动力学研究，重点是关键的O-O键裂解反应。将开发一种光化学方法，将电子快速注入到与血红素基团的铁配位的二氧化氧中。根据目前的理论，是启动这些酶的O-O键断裂的步骤。通过对所得激发态的研究，将获得有关反应中间体和O-O键断裂机理的详细信息。要研究的系统包括血红素空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。氧是一种强大的、容易获得的氧化剂，但有效利用氧的人造催化剂很少。在生化系统中发现了氧气活化和利用的最佳例子。含铁的酶负责很大程度上的生化氧活化。然而，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的氧-氧键断裂过程的机理，该过程必须位于该过程的核心。对生物系统如何运作的了解可能会使在各种实验室和工业过程中直接利用氧气的新方法成为可能。

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.