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Production, Crystallization and Structure Determination of C. difficile PPEP-1 via Microseeding and Zinc-SAD
Published on: December 30, 2016
Conformation of peroxynitrite: determination by crystallographic analysis
1Laboratorium für Anorganische Chemie, Eidgenössische Technische Hochschule, CH-8092 Zürich, Switzerland.
Chemical Research in Toxicology
|April 20, 1999
Summary
Tetramethylammonium peroxynitrite crystallizes in the cis conformation. X-ray analysis reveals a nearly flat molecule, despite crystal twinning challenges in determining precise bond parameters.
Area of Science:
- Inorganic chemistry
- Crystallography
- Biochemistry
Background:
- Peroxynitrite is a biologically significant inorganic toxin.
- It is formed in vivo from nitrogen monoxide and superoxide.
- Peroxynitrite exists in cis and trans conformations due to its nitrogen-peroxide oxygen bond.
Purpose of the Study:
- To synthesize and characterize tetramethylammonium peroxynitrite.
- To determine the crystalline conformation and structural properties of peroxynitrite.
Main Methods:
- Synthesis of tetramethylammonium peroxynitrite in ammonia.
- Slow evaporation of ammonia to promote crystallization.
- X-ray structure analysis to determine crystal structure and conformation.
Main Results:
- Tetramethylammonium peroxynitrite crystallizes in the cis conformation.
- Crystal twinning and disorder were observed, hindering precise bond length and angle determination.
- A nearly flat molecular structure (22° torsion angle) with specific bond lengths (O=N: 1.16 Å, N-O: 1.35 Å, O-O: 1.41 Å) best fits the electron density.
- The crystal space group was identified as Pmmn (59) with unit cell dimensions a = 7.1778(11) Å, b = 8.6893(13) Å, and c = 5.7266(9) Å.
Conclusions:
- The cis conformation of peroxynitrite is favored in the crystalline state.
- X-ray crystallography provides insights into the molecular geometry of peroxynitrite, despite experimental challenges.
- The structural data contributes to understanding the chemical properties and biological relevance of peroxynitrite.
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