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Myoglobin-catalyzed hydrogen peroxide dependent arachidonic acid peroxidation
Journal of Free Radicals in Biology & Medicine
|January 1, 1985
Summary
Myoglobin catalyzes lipid peroxidation using hydrogen peroxide, not superoxide. This mechanism may contribute to myocardial reperfusion injury.
Area of Science:
- Biochemistry
- Oxidative Stress
- Cardiovascular Research
Background:
- Hemeproteins, such as myoglobin, can initiate lipid peroxidation.
- Recent research shows hemeproteins can also peroxidize lipids independently of lipid hydroperoxides.
- Understanding the interaction between reactive oxygen species, myoglobin, and lipids is crucial.
Purpose of the Study:
- To investigate if myoglobin utilizes xanthine oxidase-generated superoxide and/or hydrogen peroxide to catalyze polyunsaturated fatty acid peroxidation.
- To elucidate the specific reactive oxygen species involved in myoglobin-mediated lipid peroxidation.
Main Methods:
- Studied the peroxidation of arachidonic acid catalyzed by myoglobin in the presence of hypoxanthine and xanthine oxidase.
- Compared the catalytic efficiency of oxy-myoglobin, metmyoglobin, hemoglobin, and ADP-iron chelates.
- Conducted inhibition studies to determine the role of superoxide versus hydrogen peroxide.
Main Results:
- Myoglobin catalyzes arachidonic acid peroxidation when xanthine oxidase generates superoxide and hydrogen peroxide.
- Oxy-myoglobin demonstrated the highest catalytic activity compared to other hemeproteins and chelates.
- Inhibition studies confirmed that hydrogen peroxide, not superoxide, is utilized by myoglobin to initiate peroxidation via an oxo-heme-oxidant or caged radical.
Conclusions:
- Myoglobin uses hydrogen peroxide to generate potent oxidants that initiate lipid peroxidation.
- The identified mechanism, involving myoglobin and reactive oxygen species, may play a significant role in myocardial reperfusion injury.
- Reoxygenation of ischemic heart tissue produces reactive oxygen species near myoglobin, suggesting a potential pathological pathway.
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