Kemp C M, Bardsley R G, Parr T
Division of Nutritional Sciences, School of Biosciences, Sutton Bonington Campus, The University of Nottingham, Leicestershire, LE12 5RD, UK.
J Anim Sci. 2006 Oct;84(10):2841-6. doi: 10.2527/jas.2006-163.
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.
本研究的目的是调查骨骼肌中的半胱天冬酶蛋白酶家族及其对宰后蛋白水解和肉嫩化的潜在作用。屠宰10头大白母猪，在屠宰后0、2、4、8、16、32和192小时采集腰大肌样本，并立即在液氮中速冻。随后分析样本的半胱天冬酶3/7和半胱天冬酶9活性、已知半胱天冬酶底物、α-II血影蛋白和聚（ADP-核糖）聚合酶（PARP）的蛋白质水平，以及在192小时时的剪切力。在宰后期间采集的肌肉样本免疫印迹上检测到α-II血影蛋白和PARP的特定降解产物，这些是半胱天冬酶活性和细胞凋亡的已知指标。研究了在整个宰后成熟期间观察到的半胱天冬酶活性变化与PARP和血影蛋白蛋白质水平之间的关系（n = 70）。发现在整个成熟期间α-II血影蛋白裂解产物的蛋白质水平与半胱天冬酶3/7活性（r = 0.38，P = 0.003）和半胱天冬酶9活性（r = 0.32，P = 0.012）呈正相关，表明半胱天冬酶介导的裂解在原位发生。剪切力与0至32小时的半胱天冬酶3/7（r = -0.62，P = 0.053）和半胱天冬酶9活性（r = -0.68，P = 0.044）比值之间呈负相关。此外，剪切力与半胱天冬酶产生的120 kDaα-II血影蛋白降解产物水平之间也呈负相关（r = -0.75，P = 0.012）。本研究结果表明，在成熟期间肌肉中发生了半胱天冬酶活性变化和半胱天冬酶介导的裂解，这可能与嫩肉的形成有关。
