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Nitric oxide is a physiological substrate for mammalian peroxidases
1Department of Cell Biology and Department of Cardiology, Cleveland Clinic Foundation, Cleveland, Ohio 44195, USA. abusouh@ccf.org
The Journal of Biological Chemistry
|November 25, 2000
Summary
Mammalian peroxidases, including myeloperoxidase (MPO), consume nitric oxide (NO) with hydrogen peroxide. This suggests peroxidases act as a sink for NO, impacting its availability at inflammation sites.
Area of Science:
- Biochemistry
- Enzymology
- Physiology
Background:
- Nitric oxide (NO) is a crucial signaling molecule.
- Mammalian peroxidases are involved in inflammatory and immune responses.
- The interaction between NO and peroxidases is not fully understood.
Purpose of the Study:
- To investigate NO consumption by mammalian peroxidases.
- To elucidate the role of peroxidases in NO bioavailability.
- To explore the interplay between NO and peroxidase catalysis.
Main Methods:
- Enzymatic assays measuring NO consumption.
- Stopped-flow kinetics to study enzyme-intermediate interactions.
- Use of hydrogen peroxide (H(2)O(2)) and superoxide-generating systems.
Main Results:
- Myeloperoxidase (MPO), eosinophil peroxidase, and lactoperoxidase catalytically consumed NO.
- NO consumption rates were similar with or without plasma chloride (Cl(-)).
- NO significantly altered the kinetics of MPO intermediates, particularly compound II.
Conclusions:
- Peroxidases can act as a catalytic sink for NO under physiological conditions.
- This interaction influences NO bioavailability, especially at inflammatory sites.
- A complex relationship exists between NO levels and peroxidase activity in vivo.