The interaction of short chain coenzyme Q analogs with different redox states of myoglobin

Two-equivalent oxidation of metmyoglobin (MbIII) by hydrogen peroxide (H2O2) yields an oxoferryl moiety (MbIV) plus a protein radical which presumably originates from the conversion of tyrosines to tyrosyl radicals (-MbIV). In the absence of electron donors, MbIII oxidation is followed by (i) heme d...

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Published in:The Journal of biological chemistry 1994-11, Vol.269 (44), p.27394-27400
Main Authors: Mordente, A, Santini, S A, Miggiano, A G, Martorana, G E, Petiti, T, Minotti, G, Giardina, B
Format: Article
Language:English
Subjects:
Acetylation
Aerobiosis
Animals
Heme - chemistry
Horses
In Vitro Techniques
Myoglobin - chemistry
Oxidation-Reduction
Oxygen Consumption
Spectrometry, Fluorescence
Tyrosine - chemistry
Ubiquinone - chemistry
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Summary:Two-equivalent oxidation of metmyoglobin (MbIII) by hydrogen peroxide (H2O2) yields an oxoferryl moiety (MbIV) plus a protein radical which presumably originates from the conversion of tyrosines to tyrosyl radicals (-MbIV). In the absence of electron donors, MbIII oxidation is followed by (i) heme degradation or (ii) tyrosyl radical-dependent reactions, such as irreversible dimerization or covalent binding of the heme group to the apoprotein. Moreover, the oxidizing equivalents of H2O2-activated MbIII promote the peroxidative decomposition of polyunsaturated fatty acids. In this study, water-soluble short chain coenzyme Q analogs (CoQ1H2 and CoQ2H2) were found to reduce the oxoferryl moiety, preventing heme degradation and regenerating MbIII and, more slowly, MbIIO2. CoQ1H2 and CoQ2H2 were also found to reduce tyrosyl radicals generated by UV irradiation of tyrosine solutions. Accordingly, CoQ1H2 and CoQ2H2 effectively prevented tyrosyl radical-dependent reactions such as the dimerization of sperm whale myoglobin and heme-apoprotein covalent binding in horse heart myoglobin. By competing for the oxidizing equivalents of hypervalent myoglobin, CoQ1H2 and CoQ2H2 also prevented the peroxidation of arachidonic acid. Collectively, these studies suggest that the proposed function of coenzyme Q as a naturally occurring antioxidant might well relate to its ability of reducing H2O2-activated myoglobin. Coenzyme Q should therefore mitigate cardiac or muscular dysfunctions that are caused by an abnormal generation of H2O2.
ISSN:0021-9258
1083-351X
DOI:10.1016/S0021-9258(18)46998-0