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Myoglobin scavenges peroxynitrite without being significantly nitrated.
Susanna Herold1, Kalinga Shivashankar, Martin Mehl
1Laboratorium für Anorganische Chemie, Eidgenössische Technische Hochschule, ETH Hönggerberg, CH-8093 Zürich, Switzerland. herold@inorg.chem.ethz.ch
Biochemistry
|November 6, 2002
Summary
Myoglobin and hemoglobin react with peroxynitrite. The heme center in myoglobin efficiently scavenges peroxynitrite, protecting the protein from nitration and preserving mitochondrial respiration.
Area of Science:
- Biochemistry
- Protein Chemistry
- Oxidative Stress
Background:
- Peroxynitrite is a reactive nitrogen species implicated in cellular damage.
- Hemoglobin (Hb) and myoglobin (Mb) are heme proteins involved in oxygen transport.
- Understanding protein susceptibility to oxidative modification is crucial for cellular protection mechanisms.
Purpose of the Study:
- To investigate the nitration of hemoglobin and myoglobin by peroxynitrite.
- To determine the role of different protein forms and the heme center in peroxynitrite reactions.
- To explore the protective function of oxyMb against cellular damage.
Main Methods:
- Treatment of various forms of Hb and Mb with peroxynitrite.
- High-Performance Liquid Chromatography (HPLC) analysis.
- Acid hydrolysis and Pronase digestion of proteins.
- Quantification of 3-nitrotyrosine and other nitrated amino acids.
Main Results:
- Oxy forms of Hb and Mb showed minimal 3-nitrotyrosine formation.
- Met-forms and apo-forms exhibited higher nitration levels.
- Tryptophan residues were also found to be nitrated to a detectable extent.
- The heme center of Mb acted as an efficient peroxynitrite scavenger.
Conclusions:
- The heme center of myoglobin protects the globin moiety from peroxynitrite-induced nitration.
- OxyMb may play a role in preventing mitochondrial damage by scavenging peroxynitrite.
- This mechanism offers a protective pathway against irreversible inhibition of enzymes like cytochrome c oxidase.