Determination of Metmyoglobin Reductase Activity in Bovine Skeletal Muscles

A novel technique was used to obtain an isolate of skeletal muscle containing MetMb reductase. The isolate was then used as the enzyme source in an assay procedure to measure specific MetMb reductase activity. Enzyme activity was highest at pH 6.4 as compared to 5.8 or 7.0 and at 30°C compared to 4°C. Significant differences in enzyme activity were found among beef muscles from the same animal. The order of muscles, when enzyme activity was expressed on the basis of muscle myoglobin content, was: tensor faciae latae > longissimus dorsi > gluteus medius > diaphragma medialis > semimembranosus = psoas major (p = 0.01).