Biochemical Basis of Calpain and Calpastatin Activity Determination in Blood and Tissue Samples: Potential Role in Post - Mortem Ageing of Guinea Fowl Meat

Calpain s, the calcium - dependent thiol - proteases have been implicated in various important cellular processes including tenderization of meat. So, aim of this study was to identify calpains and their potential inhibitor calpastatin in blood and skeletal muscles to elucidate their role in post - mortem tenderization of guinea fowl meat during holding at 4±1 °C. For this, breast and thigh muscles of two different guinea fowl varieties were collected, processed, and finally, analyzed on casein Zymogram gels. The sample extracts were also subjected to dialysis (12 kDa MWCO) and loaded on DEAE anion column for purification and separation of μ - and m - calpains as well as calpastatin. Results show that there were clear bands of μ - and m - calpains in the extracts of both the bl ood and muscle samples. But the band intensity for muscle samples kept decreasing with the increase of holding time showing the decreasing trend in activity of these enzymes. The calpastatin activity was also decreased rapidly and greatly. The pH and W - B s hear force values were decreased with the increase in holding time. Finally, the μ - calpain induced post - mortem maturation time was optimized at 6 h for breast and thigh muscles of both the varieties of guinea fowl.