Cis- and trans-conformations for peroxynitrite anions.

Area of Science:

• Biochemistry
• Chemical Physics
• Molecular Spectroscopy

Background:

• Peroxynitrite is a biochemically significant anion.
• It is widely believed to possess a stable cis-conformation with a cyclic structure.
• This structure is thought to prevent trans-conformation formation and favor isomerization to nitrate.

Purpose of the Study:

• To investigate the conformational stability and equilibrium of peroxynitrite.
• To challenge the prevailing view of a solely stable cis-conformation.
• To explore the potential for cis-trans isomerization in peroxynitrite.

Main Methods:

• Analysis of vibrational band linewidths at room temperature and 4 K.
• Spectroscopic characterization of peroxynitrite isomers.
• Determination of isomer lifetimes.

Main Results:

• Observed broad vibrational band linewidths at room temperature narrow significantly at 4 K.
• Indicates a rapid equilibrium between cis and trans peroxynitrite conformations.
• Isomer lifetimes were determined to be approximately 10(-12) seconds.

Conclusions:

• The cis-conformation of peroxynitrite is not uniquely stable.
• Cis and trans peroxynitrite structures exist in rapid equilibrium at room temperature.
• This finding has implications for understanding peroxynitrite's reactivity and biochemical roles.