Does oxidation affect the water functionality of myofibrillar proteins?
Water-binding properties of myofibrils extracted from porcine muscle, and added hemoglobin with and without exposure to H2O2, were characterized using low-field proton NMR T2 relaxometry. The effects of pH and ionic strength in the samples were investigated as pH was adjusted to 5.4, 6.2, and 7.0 and ionic strength was adjusted to 0.29, 0.46, and 0.71 M, respectively. The formation of dityrosine as a measure of oxidative protein cross-linking revealed a significant increase in dityrosine concentrations upon H2O2 activation. The formation of dityrosine was strongly pH-dependent and increased with decreasing pH. In addition, increased levels of thiobarbituric acid reactive substances were observed upon addition of H2O2, implying that lipid oxidation was enhanced, however, with a different oxidation pattern as compared to the myofibrillar proteins. Low-field NMR relaxation measurements revealed reduced T2 relaxation times upon H2O2 activation, which corresponds to reduced water-holding capacity upon oxidation. However, a direct relationship between degree of oxidation and T2 relaxation time was not observed with various pH values and ionic strengths, and further studies are needed for a complete understanding of the effect of oxidation on myofibrillar functionality.
Bertram
Hanne Christine
HC
Research Center Foulum, Department of Food Science, Faculty of Agricultural Sciences, University of Aarhus, P.O. Box 50, DK-8830 Tjele, Denmark. HanneC.Bertram@agrsci.dk
Kristensen
Mette
M
Østdal
Henrik
H
Baron
Caroline P
CP
Young
Jette F
JF
Andersen
Henrik Jørgen
HJ
D006861:Hydrogen Peroxide / Q000494:pharmacology; D006863:Hydrogen-Ion Concentration; D015227:Lipid Peroxidation; D009682:Magnetic Resonance Spectroscopy; D009124:Muscle Proteins / Q000502:physiology*; D009210:Myofibrils / Q000737:chemistry*; D009994:Osmolar Concentration; D010084:Oxidation-Reduction; D017392:Thiobarbituric Acid Reactive Substances / Q000032:analysis; D014867:Water / Q000502:physiology*
D009124:Muscle Proteins; D017392:Thiobarbituric Acid Reactive Substances; D014867:Water; D006861:Hydrogen Peroxide