Evidence for calpastatin cleavage by calpain in postmortem porcine longissimus dorsi

Calpastatin is the endogenous inhibitor of the calcium-dependent protease family known as calpains and is thought to be an important determinant of postmortem tenderisation rates in beef, lamb and pork (Koohmaraie, 1996; Parr et al, 1999). Regulation of calpastatin is therefore of great importance if efforts to overcome unpredictable incidences of pork toughness are to succeed. Recent evidence in ovine tissue has shown that calpastatin is susceptible to fragmentation by calpains (Doumit and Koohmaraie, 1999). The ability of calpain to fragment calpastatin in porcine tissue was investigated and the consequences for pork quality are considered.