Biochemical Studies on Changes in Fish Muscle Proteins Following Temperature Acclimation

由于鱼肉中肌原纤维蛋白占肌肉总蛋白的50%以上，其性质对各种鱼肉加工的可行性及其在储藏过程中的稳定性有很大的影响。本研究旨在回答鲤鱼和金鱼肌原纤维蛋白在温度驯化过程中哪些成分和部位的变化最为关键的问题，从而为渔业提供关于鱼肌肉作为食物原料的有价值的基础信息。几个鲤鱼个体在10或30ﾟC中驯化至少1个月，并接受肌原纤维的准备。在相同的反应温度下，10ﾟC驯化鲤鱼的肌原纤维镁离子含量显著高于30ﾟC驯化鲤鱼。相比之下，经10ﾟC驯化的鲤鱼肌原纤维Ca~(2+)-~(2+)-ﾟ酶在40…℃下的热稳定性比ATPase低好几倍30ﾟC驯化的T更多。驯化后的金鱼也进行了同样的实验，得到了类似的结果。经10ﾟC驯化的鲤鱼肌球蛋白及其亚段1(S1)的肌动蛋白激活的最大起始速度(Vmax)分别高于30ﾟC驯化的鲤鱼肌球蛋白及其亚段1(S1)的最大起始速度(Vmax)，这与两驯化组之间的肌原纤维MG^&lt；2+&gt；-ATPase活性的差异一致。30ﾟC驯化的肌球蛋白和S1分别比10ﾟC驯化的肌球蛋白和S1具有更高的热稳定性。当肌球蛋白分子的一个丝状部分--杆状，用α-胰凝乳酶进行有限的蛋白降解时，10ﾟC驯化的鲤鱼在SDSPAGE中显示一条L-肌球蛋白条带。而30ﾟC驯化鲤鱼则出现3条L-肌球蛋白条带。其中一个与10ﾟC驯化的L肌球蛋白完全相同。10ﾟC驯化鲤鱼和30ﾟC驯化鲤鱼的肌球蛋白、S1重链和杆状蛋白的肽谱明显不同，表明温度驯化过程中鲤鱼肌球蛋白分子的一级结构发生了变化。较少

Since fish myofibrillar proteins account for over 50% in total muscle proteins, the feasibility of various kinds of fish meat for food processing and their stability during storage are regarded to be greatly influenced by the properties of myofibrillar proteins. This study was performed to answer the questions on which components and parts are most critical in changes of myofibrillar proteins of carp and goldfish during temperature acclimation, thus providing fisheries industry with valuable and foundamental information on fish muscles as food materials.1. Several individuals of carp were acclimated to either 10 or 30ﾟC for a minimum of 1 month and subjected to the preparation of myofibrils. Myofibrillar Mg^<2+>-ATPase activity of 10ﾟC-acclimated carp was significantly higher than that of 30ﾟC-acclimated fish when assayed at the same reaction temperatures. In contrast, the thermal stability at 40ﾟC of myofibrillar Ca^<2+->-ATPase of 10ﾟC-acclimated carp was several times lower than tha … More t of 30ﾟC-acclimated one. The similar results were obtained when acclimated goldfish were subjected to the same experiments.2. Myosin and its subfragment-1 (Sl) from 10ﾟC-acclimated carp showed a higher maximal initial velocity (Vmax) in actin-activated Mg^<2+>-ATPase activity than the 30ﾟC-acclimated counterparts, respectively, in a good agreement with the differences observed in myfibrillar Mg^<2+>-ATPase activity between the two acclimated groups. The 30ﾟC-acclimated myosin and Sl were again more thermostable than the 10ﾟC-acclimated counterparts, respectively.3. When a filamentous part of the myosin molecule, rod, was subjected to a limited proteolysis using alpha-chymotrypsin, the 10ﾟC-acclimated carp exhibited one L-meromyosin band in SDS-PAGE analysis. On the other hand, the 30ﾟC-acclimated carp gave three L-meromyosin bands. one of which was identical to the 10ﾟC-acclimated L-meromyosin.4. Peptide maps of myosin and Sl heavy chains and rod performed in SDS-gels were clearly different between 10ﾟC-and 30ﾟC-acclimated carp, suggesting that the primary structure of carp myosin molecule is altered during temperature acclimation. Less