Molecular Evolution of Respiratory Enzymes; Functional Conversion from NO Reduction to O2 Reduction

一氧化氮还原酶（NOR）是厌氧呼吸的关键酶，它催化细胞毒性NO分解为N_2O。我们测定了两种膜整合酶的晶体结构，分别是铜绿假单胞菌的cNOR和嗜热硬脂菌的qNOR。在此基础上，提出了酶促NO还原和质子转移的分子机制，并探讨了呼吸酶从厌氧到好氧系统的分子演化过程。

Nitric oxide reductase (NOR) is a key enzyme of anaerobic respiration, which catalyzes decomposition of cyt-toxic NO to N_2O. We determined the crystal structures of the membrane-integrated enzymes, cNOR from P. aeruginosa and qNOR from G. stearothermophillus. On the basis of these structures, we proposed the molecular mechanism of the enzymatic NO reduction and the proton transfer, and discussed the molecular evolution of the respiratory enzymes from anaerobic to aerobic systems.