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.