Interactions between carnosine and the different redox states of myoglobin

To better understand the mechanism by which carnosine inhibits myoglobin oxidation in salted ground pork, interactions of carnosine with ferrylmyoglobin (ferMb), metmyoglobin (metMb) and oxymyoglobin (oxyMb) were investigated. Carnosine (0-50 mM; pH 5.0-7.5) accelerated the conversion of metMb to oxyMb at pH greater than or equal to 7.0 and carnosine concentrations greater than or equal to 25 mM. Carnosine (1-50 mM) also accelerated the conversion of oxyMb to metMb with its formation rates increasing with decreasing pH and increasing carnosine concentrations. Carnosine (1-25 mM) inhibited ferMb-catalyzed oxidation of phosphatidylcholine liposomes 16-76% and reduced the ferMb electron paramagnetic resonance signal 24-43%. Results suggested that the color stabilizing effects of carnosine were related to its antioxidant activity.