Spectroscopic and Computational Study of a Nonheme Iron Nitrosyl Center in a Biosynthetic Model of Nitric Oxide Reductase1. Issue 9 (31st January 2014)

• Record Type: Journal Article
• Authors: Chakraborty, Saumen; Reed, Julian; Ross, Matthew; Nilges, Mark J.; Petrik, Igor D.; Ghosh, Soumya; Hammes‐Schiffer, Sharon; Sage, J. Timothy; Zhang, Yong; Schulz, Charles E.; Lu, Yi
• Is Part Of: Angewandte Chemie international edition. Volume 53:Issue 9(2014)
• Page Start: 2417
• Page End: 2421
• Publication Date: 2014-01-31
• Subjects: Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201308431
• Languages: English
• ISSNs: 1433-7851

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>Abstract</title> <p>A major barrier to understanding the mechanism of nitric oxide reductases (NORs) is the lack of a selective probe of NO binding to the nonheme Fe_B center. By replacing the heme in a biosynthetic model of NORs, which structurally and functionally mimics NORs, with isostructural ZnPP, the electronic structure and functional properties of the Fe_B nitrosyl complex was probed. This approach allowed observation of the first <italic>S</italic>=3/2 nonheme {FeNO}⁷ complex in a protein‐based model system of NOR. Detailed spectroscopic and computational studies show that the electronic state of the {FeNO}⁷ complex is best described as a high spin ferrous iron (<italic>S</italic>=2) antiferromagnetically coupled to an NO radical (<italic>S</italic>= 1/2) [Fe²⁺‐NO^.]. The radical nature of the Fe_B‐bound NO would facilitate NN bond formation by radical coupling with the heme‐bound NO. This finding, therefore, supports the proposed <italic>trans</italic> mechanism of NO reduction by NORs.</p> </abstract>