Key Laboratory of Meat Processing and Quality Control, Ministry of Education, Nanjing Agricultural University, Nanjing 210095, China.
Meat Sci. 2011 Mar;87(3):165-74. doi: 10.1016/j.meatsci.2010.10.002. Epub 2010 Oct 14.
Recently, a novel consideration has focused on the potential relationship of apoptosis and the protease caspases and the underlying mechanism for meat postmortem tenderization. In this study, apoptosis inducers, camptothecin and etoposide as well as Ca(2+) were used to treat chicken muscle immediately after slaughter and follow the changes in caspase-3 activities and changes in the myofibrillar structures during 7 days of ageing. All three treatments resulted in significantly higher caspase-3 activities during storage (p<0.05), with the natural substrates, whereas Western blotting analysis of the α-spectrin cleavage product, 120 kDa peptide (SBDP 120), showed that Ca(2+) was more effective than either camptothecin or etopside, and all were most active up to day 3 (p<0.01). According to SDS-PAGE, each treatment enhanced the accumulation of the 30 kD Troponin-T degradation product, especially during the first 3 days (p<0.05), and this was supported by the degradation of myofibrils observed by electron microscopy (TEM). TEM images showed the treatments resulted in enlargement of the I-bands and shrinkage of A-bands; however Z-lines were only slightly affected, even at day 7. The findings revealed that the three apoptosis inducers could increase myofibrillar dissociation and proteolysis during the first 3 days of chicken meat ageing. Because of the high activity of caspase-3 during the early postmortem period, it is possible that caspase-3 contributes to the conversion of muscle into meat.
最近，人们关注细胞凋亡与半胱天冬氨酸蛋白酶(caspases)的潜在关系及其在肉品宰后嫩化过程中的作用机制。本研究采用喜树碱和依托泊苷等细胞凋亡诱导剂以及 Ca(2+)即刻处理宰后鸡肉，研究其对鸡肉宰后成熟过程中 caspase-3 活性变化及肌原纤维结构的影响。结果表明，3 种处理均能显著提高鸡肉成熟过程中 caspase-3 活性（p<0.05），其中以 Ca(2+)诱导的 caspase-3 活性最高，且在第 3 天达到峰值；Western blot 分析发现，3 种处理均能诱导肌动蛋白特异性半胱氨酸蛋白酶抑制剂α- spectrin 的裂解，产生 120 kDa 的多肽（SBDP 120），且 Ca(2+)的诱导效果最强，喜树碱和依托泊苷次之；SDS-PAGE 分析发现，3 种处理均能促进 30 kD 肌钙蛋白 T 降解产物的积累，且在成熟初期（第 1-3 天）最为显著（p<0.05），电镜观察结果进一步证实了这一现象。电镜结果显示，3 种处理均能导致 I 带增宽、A 带变窄，而 Z 线仅在第 7 天出现轻微变化；以上结果表明，3 种凋亡诱导剂能够促进鸡肉宰后成熟过程中肌原纤维的解离和降解。由于 caspase-3 在宰后早期具有较高的活性，因此推测其可能参与了肌肉向肉的转化过程。
