Comparative effects of post‐mortem storage and low‐calcium‐requiring neutral proteinase on bovine and rabbit myofibrillar proteins

Abstract The effects of post‐mortem storage and of a low‐calcium‐requiring neutral proteinase on the myofibrils of beef Longissimus dorsi and Rectus abdominis muscles and rabbit Longissimus dorsi muscle were studied by measuring the Mg‐Ca‐enhanced myofibrillar ATPase activity and the changes in banding patterns on electrophoresis in sodium dodecyl sulphate. During ageing, the changes in the ATPase activity and myofibrillar proteins were qualitatively different between rabbit and bovine muscles, whilst differences in intensity were only observed between the two bovine muscles. The most prevalent component appearing upon conditioning had a mol. wt of 27 000 in rabbit muscle and of 30 000 in bovine muscles. In both species, the incubation of myofibrils with the low‐calcium‐requiring neutral proteinase mimicked the post‐mortem changes. This would suggest that this enzyme has a qualitatively different effect on rabbit and bovine myofibrils.