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Myoglobin-catalyzed tyrosine nitration: no need for peroxynitrite
1Department of Molecular and Cellular Physiology, Louisiana State University Health Sciences Center, Shreveport, LA 7113, USA.
Biochemical and Biophysical Research Communications
|July 11, 2001
Summary
Myoglobin catalyzes tyrosine nitration, forming 3-nitrotyrosine independently of peroxynitrite. This reaction is hydrogen peroxide-dependent and favored in the acidic conditions of myocardial ischemia.
Area of Science:
- Biochemistry
- Oxidative Stress Research
- Cardiovascular Science
Background:
- 3-nitrotyrosine formation is a marker for in vivo peroxynitrite.
- Hemoproteins like peroxidases can catalyze tyrosine nitration independently of peroxynitrite.
- 3-nitrotyrosine is found in post-ischemic heart tissue.
Purpose of the Study:
- To investigate myoglobin's potential to catalyze tyrosine nitration in vitro.
- To determine if myoglobin-mediated 3-nitrotyrosine formation is peroxynitrite-dependent.
Main Methods:
- In vitro experiments assessing myoglobin's catalytic activity.
- Measurement of nitrite oxidation and tyrosine nitration.
- Evaluation of hydrogen peroxide dependence and pH effects.
Main Results:
- Myoglobin catalyzes the oxidation of nitrite and nitration of tyrosine.
- Both reactions are dependent on hydrogen peroxide and ferryl myoglobin formation.
- Optimal conditions for these reactions occur at pH 6.0.
Conclusions:
- Myoglobin can catalyze the formation of 3-nitrotyrosine in a peroxynitrite-independent manner.
- Acidic pH and low oxygen tension during myocardial ischemia favor myoglobin-catalyzed 3-nitrotyrosine production.