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Myoglobin as an Endogenous Inhibitor of Proteolytic Muscle Enzymes

Abstract:

The effect of myoglobin content on the activity of different proteolytic systems, lysosomal enzymes, calcium dependent neutral proteinases, and aminopeptidases was examined concretely. Increasing myoglobin content inhibited cathepsin activities (B, B + L, and H). A similar effect was obtained with μ-calpain, which showed about 10% of its initial activity in the presence of 1 mg/mL of myoglobin. In contrast, m-calpain and calpastatin were almost insensitive to different levels of myoglobin in the medium. Exopeptidases, aminopeptidase B and alanyl aminopeptidase, were inhibited by myoglobin to approximately the same extent as the cathepsins. These results suggest that myoglobin might be considered an endogenous inhibitor, which could affect the endogenous proteolytic activity differently in different types of muscles. Consequently, the rate of both meat tenderization and generation of free amino acids may also be regulated by myoglobin.