Changes in caspase activity during the postmortem conditioning period and its relationship to shear force in porcine longissimus muscle1

Abstract

The objective of this study was to investigate the protease family caspases in skeletal muscle and their potential contribution to postmortem proteolysis and meat tenderization. Ten Large White gilts were slaughtered, and samples of LM were taken at 0, 2, 4, 8, 16, 32, and 192 h after slaughter and immediately snap frozen in liquid nitrogen. Samples were subsequently analyzed for caspase 3/7 and caspase 9 activity, protein levels of known caspase substrates, alpha II spectrin and poly (ADP-ribose) polymerase (PARP), as well as, at 192 h, shear force. Specific degradation products of alpha II spectrin and PARP, which are known indicators of caspase activity, and apoptosis were detected on immunoblots of muscle samples taken over the postmortem period. The relationships between the changes observed in caspase activities and protein levels of PARP and spectrin across the entire postmortem conditioning period were investigated (n = 70). Protein levels of alpha II spectrin cleavage products across the conditioning period were found to correlate positively to caspase 3/7 activity (r = 0.38, P = 0.003) and caspase 9 activity (r = 0.32, P = 0.012), indicating that caspase-mediated cleavage was occurring in situ. There was a negative relationship between shear force and the 0 to 32 h ratio of caspase 3/7 (r = -0.62, P = 0.053) and caspase 9 activities (r = -0.68, P = 0.044). In addition, there was also a negative relationship between shear force and the level of the caspase-generated alpha II spectrin 120 kDa degradation product (r = -0.75, P = 0.012). The findings of this study indicate that changes in caspase activity and caspase-mediated cleavage take place in muscle during the conditioning period, and this could be associated with the development of tender meat.

The effect of calcium chloride injection on shear force and caspase activities in bovine longissimus muscles during postmortem conditioning

“…Caspases Caspase-9. There was a significant decrease in caspase-9 activity from 4 h to day 2 in both control and treated samples (P , 0.001; Figure 3), similar to those reported in postmortem porcine LM muscle by Kemp et al (2006). The caspase-9 activity varied significantly among the treated and control samples at 4 h and day 4 (P , 0.01).…”

“…The caspase-3 activity significantly increased from 4 h to day 1, whereas subsequently decreased from days 1 to 2 in control (P , 0.001; Figure 5). Similarly, Kemp et al (2006) reported that there was a general decrease in caspase-3/7 activity over storage with the highest activity at 2 h in pork. In addition, Underwood et al (2008) indicated that caspase-3 activity decreased at days 3 and 10 post mortem when compared with 0 day in beef.…”

“…The decrease of caspase-9 activity in porcine LM muscle and that of caspase-3 in porcine LM muscle and bovine m. longissimus thoracis muscle were reported during postmortem conditioning (Kemp et al, 2006;Underwood et al, 2008). During postmortem ischemia, intracellular ATP is rapidly degraded as a result of insufficient oxygen supply and rapid consumption of glycogen (Shen et al, 2006); whereas the availability of intracellular ATP is necessary for the activation of caspases.…”

Activation of caspase-9 and its influencing factors in beef during conditioning

“…Ouali et al (2006) suggested that the cysteine protease family of caspases is in a better position than other proteolytic enzymes to cleave cytoskeleton, as this is their primary function in vivo. Kemp et al (2006a) indicated that caspasemediated cleavage takes place in the porcine muscles during conditioning. Kemp et al (2006b) detected caspase-3 (20 kDa) and caspase-8 (18 kDa) active fragments in the porcine muscles.…”

Influence of ultrasound and proteolytic enzyme inhibitors on muscle degradation, tenderness, and cooking loss of hens during aging

“…Kemp et al (2006) investigated the relevant expression of various caspase types in different porcine skeletal muscles and reported the direct involvement of the caspase family in meat tenderisation. Moreover, Huang et al (2009) made use of DEVD-CHO (N-acetylAsp-Glu-Val-Asp-CHO), a selective inhibitor of caspase-3, and showed that it dramatically reduced the degradation of the skeletal proteins, such as nebulin, titin, troponin-T, and desmin, while the activity of calpain was not affected.…”