Modeling Side-On NO Coordination to Type 2 Copper in Nitrite Reductase: Structures,Energetics,and Bonding

摘要

Recent crystallographic studies by Murphy,Hasnain,and their co-workers have led to major insights into the mechanism of copper nitrite reductase (CuNIR),one of two bacterial enzymes (the other being a heme nitrite reductase) that reduce nitrite to NO.The key new result consists of high-resolution CuNIR crystal structures with side-on NO coordination to the catalytically active type 2 copper,which is a unique structural motif in copper coordination chemistry.Though rare,side-on NO coordination has been previously observed,for example,in the photoisomer of a {RuNO} porphyrin,which has been characterized by low-temperature IR spectroscopy.