鸡肉在成熟过程中肌原纤维蛋白的降解机制研究

Mechanism of myofibrillar proteins degradation during chicken postmortem aging

为了探讨肉在成熟过程中肌原纤维蛋白的降解机制,五只肉鸡分别宰杀后,迅速取出胸肉约3 g为0 d样品,其余肉样剪碎后随机分成六组,一组作为对照,另5组分别用30 mmol/L EGTA、20 mmol/L CaCl2、酶复合抑制剂、100μmol/L细胞凋亡酶3抑制剂(DEVD-CHO)、20 mmol/L CaCl2和酶复合抑制剂处理,在4℃成熟1、3、7 d后取样。通过SDS-PAGE和蛋白质印迹分析测定了骨骼肌中和肉嫩度高度相关的拌肌球蛋白(titin)、伴肌动蛋白(nebulin)、肌间线蛋白(desmin)、肌钙蛋白T(troponin-T)的降解变化。结果显示蛋白水解酶复合抑制剂和DEVD-CHO抑制了蛋白的降解,单独的钙离子加速蛋白降解。这表明肉的成熟是内源酶的作用,钙离子很可能通过激活钙激活酶发挥作用,另外细胞凋亡酶3也很可能参与了肉的成熟。

In order to investigate the mechanism underlying postmortem proteolysis of muscle proteins during meat aging, five broilers were slaughtered and treated individually. After breast muscles were removed, the samples at death were obtained quickly. The other muscles were dissected into small blocks and divided into six groups randomly. One group marinated in solution containing 100 mmol/L NaCl and 2 mmol/L NaN3 was designated as control, the others were soaked in solutions as controls but containing 30 mmol/L EGTA, 20 mmol/L CaCl2, protease inhibitor cocktail （10 mL/tablet）, 100 μmol/L caspase3 selective inhibitor （DEVD-CHO）, 20 mmol/L CaCl2 plus protease inhibitor cocktail, respectively in the ratio 1 ： 1（W/V） （meat ： solution）, then stored at 4℃ for 1, 3, 7 d. At each conditioning time point, meat samples were obtained, and the changes of myofibril proteins （titin, nebulin, desmin, and troponin-T） were examined by SDS-PAGE and western blotting. Results reveal that proteases inhibitor cocktail and DEVD-CHO inhibit myofibril proteins digestion markedly, whereas calcium accelerated the process implying that the endogenous proteases contribute to meat protein degradation, calcium may play a role by activating calpains and that the apoptosis related caspase-3 is possibly another new biological candidate involved in meat tenderization.