鲢鱼背肌肌原纤维蛋白自溶与内源组织蛋白酶B,L,H的关系

Preliminary study of the relationship between autolysis of silver carp (Hypophthalmichthys molitrix) myofibrillar proteins and endogenous cathepsins B,L and H

鲢鱼鱼糜制品在加工过程中容易发生热诱导 (5 0～ 70℃ )的鱼糜凝胶软化 (modori) ,导致鱼糜制品品质下降。为探明原因 ,本研究比较了在加工过程中漂洗前后鲢鱼鱼肉糜中组织蛋白酶B ,L ,H活性的变化 ,结果表明漂洗后仍残留了组织蛋白酶B ,L ,H活性 ,其中组织蛋白酶L活性的残留率最高 ,为 2 5 6 1%± 0 82 %。用SDS PAGE分析了有无E 6 4存在下 ,鲢鱼背肌肌原纤维蛋白自溶过程中 (pH 6 5 ,5 0℃ ) ,肌球蛋白重链相对含量的差异 ,结果显示肌球蛋白重链相对含量的下降趋势与残留的组织蛋白酶活性变化趋势吻合 ;而且E 6 4部分抑制了肌球蛋白重链的自溶。上述结果表明溶酶体半胱氨酸组织蛋白酶在鲢鱼鱼糜凝胶软化中起一定作用 ,而且组织蛋白酶L可能是重要的蛋白水解酶。

During silver carp surimi processing, considerable gel softening often occurs due to heating, and results in poor textural quality of surimi products.This study was an attempt to investigate the reason through comparing the activities of cathepsin B,L,H in the silver carp mince before and after washing. Our results showed that there were still some cathepsin B, L, H activities after washing, 11.30%±1.27%, 25.61%±0.82% and 6.89%±0.44% respectively. The SDS-PAGE analysis with and without E-64 indicated that the reduction of the relative quantity of myosin high chain (MHC) was consistent with the rudimentary catheptic activities during autolysis (pH 6.5,50℃)of silver carp dorsal muscle E-64 partly inhibited the autolysis of myosin high chain (MHC). It was suggested that the modori of silver carp surimi was partly induced by the thiol cathepsins in muscle lysosome, especially cathepsin L.