Metmyoglobin reductase activity in bovine muscles.

Cow muscles (Longissimus dorsi, Tensor fasciae latae, Psoas major, Diaphragma medialis), with different colour stabilities, were used to measure 'Metmyoglobin reductase activity' in different conditions. The effects of pH and temperature on in vitro metmyoglobin reduction were analysed. The highest metmyoglobin reductase activity was localized in microsomes and in more or less intact mitochondria by means of differential centrifugations. The most unstable muscles, from the colour point of view, presented the highest reducing activities and no differences were noted between activities measured in aerobic or anaerobic conditions.