Department of Animal Science, National Chiayi University, Chiayi City, 60083 Taiwan.
J Sci Food Agric. 2012 Jun;92(8):1620-6. doi: 10.1002/jsfa.4747. Epub 2011 Dec 9.
It is generally agreed that calpains are involved in postmortem proteolysis of skeletal muscle and improve meat tenderness. However, little information regarding the postmortem role of calpains in duck skeletal muscle is known. Therefore, the purpose of this study was to examine the role of calpains in Pekin duck postmortem breast muscles (BM) and leg and thigh muscles (LM) muscles at 5 °C.
The postmortem pH was lower (P < 0.05) in BM than in LM. Western blots indicated that postmortem desmin degradation and the 30/32 kDa troponin-T degradation product accumulation were more rapid in BM than in LM. Casein zymograms showed that at-death µ-calpain activity was higher in BM than in LM. As time post mortem increased, µ-calpain was activated and autolyzed more rapidly and extensively in BM than in LM, but µ/m-calpain was activated at a relative slower rate compared with µ-calpain. Correlation results showed that µ-calpain activity, rather than µ/m-calpain activity, in BM samples was highly correlated with the abundance of desmin and the 30/32 kDa troponin-T degradation components across the postmortem period. However, no such correlations were found with LM µ- and µ/m-calpains.
Therefore, our results suggest that BM µ-calpain with a faster and more extensive activation and autolysis would play a relatively dominant role in dictating degradation of desmin and troponin-T in postmortem duck muscle.
普遍认为钙蛋白酶参与死后骨骼肌的蛋白水解作用，可改善肉的嫩度。然而，关于钙蛋白酶在鸭骨骼肌中的死后作用的信息知之甚少。因此，本研究旨在研究钙蛋白酶在 5°C 条件下对北京鸭胸肌（BM）和腿肌及大腿肌（LM）中的作用。
BM 的死后 pH 值低于 LM（P＜0.05）。Western blot 表明，BM 中肌联蛋白-T 的 30/32 kDa 降解产物的积累比 LM 中更快。酪蛋白酶谱显示，BM 中的钙蛋白酶µ-活性高于 LM。随着死后时间的增加，µ-钙蛋白酶在 BM 中的激活和自溶比在 LM 中更快、更广泛，但 µ/m-钙蛋白酶的激活速度相对较慢。相关性结果表明，在 BM 样本中，µ-钙蛋白酶活性与死后期间肌联蛋白-T 的 30/32 kDa 降解产物的含量呈高度相关，而 µ/m-钙蛋白酶活性则没有相关性。
因此，我们的结果表明，BM 中的 µ-钙蛋白酶具有更快、更广泛的激活和自溶作用，在决定死后鸭肌肉中肌联蛋白-T 和肌联蛋白-T 的降解方面发挥着相对主导的作用。
