76D-1 |
The effect of glutathione on oxymyoglobin oxidation |
J. TANG, C. Faustman, and T. Hoagland. Department of Animal Science, University of Connecticut, 3636 Horsebarn Hill Road Ext, Storrs, CT 06269 Glutathione (GSH), an important cellular antioxidant, can scavenge free radicals and protect cell membranes and proteins from oxidation. This study was designed to investigate: 1) the effect of GSH on equine oxymyoglobin (Oxymb) oxidation, and 2) the effect of GSH on Oxymb oxidation in bovine muscle cytosol. In experiment 1, equine Oxymb was incubated with GSH (0, 0.05, 0.2, 0.8 mM) at pH 5.6 or 7.2, and 25 °C or 37 °C. In experiment 2, beef biceps femoris muscle was ground, homogenized with buffer, centrifuged (30 min @ 100,000 g), and GSH incubated with cytosolic supernatant at 4 °C or 25 °C. In experiment 3, high molecular weight (HMW) and low molecular weight (LMW) fractions were obtained from cytosolic extract by membrane separation (10 kDa MWCO), and incubated with GSH at pH 7.2, 25 °C. Cytosol and HMW fractions were also heated at 90 °C for 15 min and subsequently incubated with GSH and equine Oxymb at pH 7.2, 25 °C. Oxymb oxidation was measured spectrophotometrically and reported as metmyoglobin (Metmb) formation. GSH accelerated equine Oxymb oxidation in vitro at both pH 7.2 and 5.6 (p<0.05). However, GSH addition to the unheated cytosolic extract and HMW fraction resulted in delayed Metmb formation versus controls (p<0.05). There was no effect of GSH addition on equine Oxymb oxidation in LMW, heated HMW or heated cytosolic extract (p>0.05). These results suggest that GSH antioxidant activity toward Oxymb in muscle cytosol is related to a HMW constituent that is inactivated by heat.
Session 76D, Muscle Foods II
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