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Microperoxidase 8 catalyzed nitration of phenol by nitrogen dioxide radicals

R Ricoux1, J L Boucher, D Mansuy

  • 1Laboratoire de Chimie et Biochimie Pharmacologiques et Toxicologiques, UMR 8601 CNRS, Université Paris V, France.

European Journal of Biochemistry
|July 4, 2001
PubMed

Insights

Microperoxidase 8 (MP8), a heme octapeptide, catalyzes phenol nitration using nitrite and hydrogen peroxide. This minienzyme

Area of Science:

  • Biochemistry
  • Organic Chemistry
  • Enzymology

Background:

  • Microperoxidase 8 (MP8) is a heme octapeptide derived from cytochrome c.
  • MP8 exhibits peroxidase-like and cytochrome P450-like activities due to high-valent iron-oxo species formation.
  • These activities are facilitated by the replacement of axial ligands with hydrogen peroxide (H2O2).

Purpose of the Study:

  • To investigate the catalytic activity of MP8 in the nitration of phenol using nitrite.
  • To elucidate the mechanism and reactive species involved in MP8-catalyzed nitration.
  • To explore MP8 as a biomimetic catalyst for synthesizing nitro-aromatic compounds.

Main Methods:

  • MP8 was used as a catalyst in the presence of phenol, nitrite, and H2O2.
  • The reaction was studied under varying conditions, including the addition of inhibitors.
  • Inhibitors included ligands with high iron affinity, catalase, and radical scavengers.

Main Results:

  • MP8 successfully catalyzed the nitration of phenol by nitrite in the presence of H2O2.
  • The reaction was inhibited by catalase, radical scavengers, and high-affinity iron ligands.
  • Results suggest the involvement of NO2* radicals, formed by nitrite oxidation via high-valent iron-oxo species.

Conclusions:

  • MP8 demonstrates a novel catalytic activity for nitrating phenol with nitrite.
  • The mechanism likely involves NO2* radicals generated by MP8's high-valent iron-oxo intermediates.
  • MP8 serves as a valuable minienzyme for biomimicking heme peroxidases in reactions involving NO-derived species and biomolecules under oxidative stress.

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