Studies of Desmin and α-Actinin Degradation in Bovine Semitendinosus Muscle

The degradation of desmin and α-actinin was studied in post-mortem bovine semitendinosus muscle. Using a desmin-specific monoclonal antibody, SDS-PAGE, and immunoblotting we show that desmin is easily degraded at 4°C during the aging process. Within 96 hr, fragments of degraded desmin are detected with our antibody probe. Further storage at 4°C results in an increase of proteolytic fragments and concomitant loss of intact desmin. By 3 wk post-mortem, little un-degraded desmin remains in the muscle. In contrast, α-actinin was degraded slowly at 4°C. Proteolytic fragments of α-actinin were not detectable with anti-α-actinin polyclonal antisera until the second week of incubation at 4°C. However, the degradation of α-actinin was accelerated when meat was incubated at 25°C or at 37°C.