Related Experiment Video
Updated: Jun 17, 2026
![Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase](/_next/image?url=https%3A%2F%2Fcloudfront.jove.com%2FCDNSource%2Fteasers%2F55858.jpg&w=3840&q=50)
Protein Film Infrared Electrochemistry Demonstrated for Study of H2 Oxidation by a [NiFe] Hydrogenase
Published on: December 4, 2017
Reductive coupling of nitrogen monoxide (*NO) facilitated by heme/copper complexes
Jun Wang1, Mark P Schopfer, Simona C Puiu
1Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA.
This study demonstrates nitric oxide (NO) reductive coupling at a heme/copper active site, mimicking nitric oxide reductase (NOR) biochemistry. The reaction produces N2O, showcasing the essential roles of both iron and copper centers.
Area of Science:
- Bioinorganic Chemistry
- Organometallic Chemistry
- Biochemistry
Background:
- Interactions of nitrogen monoxide (NO) with transition metals are crucial in biological processes.
- Heme/copper active sites in enzymes like cytochrome c oxidases (CcOs) play significant roles in these interactions.
- Understanding nitric oxide reductase (NOR) biochemistry is vital for comprehending NO metabolism.
Purpose of the Study:
- To investigate the reductive coupling chemistry of gaseous nitric oxide (NO) at a model heme/copper active site.
- To elucidate the mechanism relevant to nitric oxide reductase (NOR) biochemistry.
- To characterize the intermediate dinitrosyl species and the final products of the reaction.
Main Methods:
- Synthesis and characterization of a heme complex, (F(8))Fe(NO), and a copper complex, [(tmpa)Cu(I)(MeCN)](+).
- Spectroscopic monitoring (UV-vis, EPR, NMR) of reactions involving gaseous NO, heme, and copper complexes.
- X-ray crystallography to characterize a related iron complex, [(F(8))Fe(III)]SbF(6).
Main Results:
- Formation of a reversible heme dinitrosyl species, (F(8))Fe(NO)(2), from the mononitrosyl complex.
- Reductive coupling of 2 NO molecules by the heme/copper system in the presence of acid, yielding N(2)O, Fe(III), and Cu(II).
- Demonstration that both iron and copper centers are essential for the NOR-type chemistry.
Conclusions:
- The study successfully models the reductive coupling of nitric oxide (NO) at a heme/copper active site, relevant to NOR biochemistry.
- The reaction stoichiometry, 2NO + Fe(II) + Cu(I) + 2H+ → N(2)O + Fe(III) + Cu(II) + H(2)O, was confirmed.
- Absence of acid leads to NO trapping or disproportionation, highlighting the importance of protonation in the catalytic cycle.
More Related Videos
08:23Chemiluminescence-based Assays for Detection of Nitric Oxide and its Derivatives from Autoxidation and Nitrosated Compounds
Published on: February 16, 2022
12:08Monitoring the Reductive and Oxidative Half-Reactions of a Flavin-Dependent Monooxygenase using Stopped-Flow Spectrophotometry
Published on: March 18, 2012
Related Concept Videos
Preparation of Amines: Reduction of Oximes and Nitro Compounds
Though catalytic hydrogenation can reduce nitrobenzenes, the reduction is nonselective in the presence of other functional groups. For instance, if nitrobenzene contains an aldehyde group,...
Electron Transport Chain: Complex III and IV
Cofactors and Coenzymes
Cofactors can be metallic ions or organic molecules called coenzymes. These types of helper...
Phase I Reactions: Reductive Reactions
Catalysis
Catalysis