Investigation of the mechanism of heme degradation by heme oxygenase-1

血红素加氧酶（HO）通过三个连续的单加氧酶反应催化血红素的降解。为探究HO反应中间体亚铁a-铁素的氧化卟啉环的裂解机制，在厌氧条件下制备了铁a-铁素-大鼠HO-1配合物。在厌氧条件下对该配合物进行了电化学还原，并测定了绿铁素中磷卟啉环的单电子还原电位。研究了CO等配体对nadph -细胞色素P450还原酶的电化学还原和电子转移的影响。此外，还测定了大鼠HO-1与亚铁a -蛇麻素配合物的晶体结构。在实验结果的基础上，探讨了生理条件下亚铁绿铁素的降解机理。

Heme oxygenase (HO) catalyses the degradation of heme via three successive monooxygenase reactions. To probe the cleavage mechanism of oxaporphyrin ring of ferrous a-verdoheme, an intermediate in the HO reaction, ferrous verdoheme-rat HO-1 complex was prepared under anaerobic conditions. Electrochemical reduction of the complex was performed under anaerobic conditions and the reduction potential for one-electron reduction of the oxaporphyrin ring of ferrous verdoheme was determined. Effects of ligands such as CO on the electrochemical reduction and the electron transfer from NADPH-cytochrome P450 reductase to the complex were investigated. In addition, the crystal structure of rat HO-1 in complex with ferrous a -verdoheme was determined. On the basis of results in these experiments, the degradation mechanism of ferrous verdoheme under the physiological condition has discussed.