Reduction of Ferrylmyoglobin by Hydrogen Sulfide. Kinetics in Relation to Meat Greening

The hypervalent meat pigment ferrylmyoglobin, MbFe(IV)O, characteristic for oxidatively stressed meat and known to initiate protein cross-linking, was found to be reduced by hydrogen sulfide to yield sulfmyoglobin. Horse heart myoglobin, void of cysteine, was used to avoid possible interference fro...

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Bibliographic Details
Published in:Journal of agricultural and food chemistry 2013-03, Vol.61 (11), p.2883-2888
Main Authors: Libardi, Silvia H, Pindstrup, Helene, Cardoso, Daniel R, Skibsted, Leif H
Format: Article
Language:English
Subjects:
activation energy
Animals
Biological and medical sciences
catalytic activity
crosslinking
cysteine
Food industries
Fundamental and applied biological sciences. Psychology
heart
Horses
hydrogen sulfide
Hydrogen Sulfide - chemistry
Hydrogen-Ion Concentration
Kinetics
meat
Meat - analysis
Meat and meat product industries
Metmyoglobin - chemistry
myoglobin
Oxidation-Reduction
temperature
thiols
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Summary:The hypervalent meat pigment ferrylmyoglobin, MbFe(IV)O, characteristic for oxidatively stressed meat and known to initiate protein cross-linking, was found to be reduced by hydrogen sulfide to yield sulfmyoglobin. Horse heart myoglobin, void of cysteine, was used to avoid possible interference from protein thiols. For aqueous solution, the reactions were found to be second-order, and an apparent acid catalysis could be quantitatively accounted for in terms of a fast reaction between protonated ferrylmyoglobin, MbFe(IV)O,H+, and hydrogen sulfide, H2S (k 2 = (2.5 ± 0.1) × 106 L mol–1 s–1 for 25.0 °C, ionic strengh 0.067, dominating for pH < 4), and a slow reaction between MbFe(IV)O and HS– (k 2 = (1.0 ± 0.7) × 104 L mol–1 s–1 for 25.0 °C, ionic strengh 0.067, dominating for pH > 7). For meat pH, a reaction via the transition state {MbFe(IV)O···H···HS}⧧ contributed significantly, and this reaction appeared almost independent of temperature with an apparent energy of activation of 2.1 ± 0.7 kJ mol–1 at pH 7.4, as a result of compensation among activation energies and temperature influence on pK a values explaining low temperature greening of meat.
ISSN:0021-8561
1520-5118
DOI:10.1021/jf305363e