TY - JOUR
T1 - Reduction of Ferrylmyoglobin by Hydrogen Sulfide. Kinetics in Relation to Meat Greening
AU - Libardi, Silvia H.
AU - Kristensen, Helene Pindstrup
AU - Cardoso, Daniel R.
AU - Skibsted, Leif Horsfelt
PY - 2013/3/20
Y1 - 2013/3/20
N2 - 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 (k2 = (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- (k2 = (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 pKa values explaining low temperature greening of meat.
AB - 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 (k2 = (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- (k2 = (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 pKa values explaining low temperature greening of meat.
U2 - 10.1021/jf305363e
DO - 10.1021/jf305363e
M3 - Journal article
C2 - 23425699
SN - 0021-8561
VL - 61
SP - 2883
EP - 2888
JO - Journal of Agricultural and Food Chemistry
JF - Journal of Agricultural and Food Chemistry
IS - 11
ER -