Mechanism of catalytic nitric oxide reduction by membrane-bound nitric oxide reductase : comparison with oxygen reduction reaction

用X射线晶体学方法测定了参与无氧呼吸链的还原型和CN结合型氧化型一氧化氮还原酶（NOR）的结构。共振拉曼光谱表明底物NO以弯曲构象与活性中心血红素结合。通过分子动力学模拟研究了质子转移机理，揭示了NOR中控制催化质子转移的结构因素。这些发现有助于我们理解NOR中NO还原反应的分子机制，以及在分子进化过程中NOR向有氧呼吸酶的功能转化。

Structures of reduced and CN-bound oxidized nitric oxide reductase(NOR), which is involved in anaerobic respiration chain, were determined by X-ray crystallography. Resonance Raman measurement indicated that the substrate, NO, bound to the active site heme in a bent conformation. The proton transfer mechanism was also examined by molecular dynamics simulation, suggesting the structural factor(s) controlling the catalytic proton transfer in NOR. These findings help us understanding the molecular mechanism of the NO reduction reaction in NOR and the functional conversion from NOR to aerobic respiration enzyme during the molecular evolution.