【摘要】 对来自春季(4月份)、夏季(8月份)、秋季(11月份)和冬季(1月份)的草鱼(Ctenopharyngodonidellus)和鲢(Hypophthalmichthys molitrix)骨骼肌肌球蛋白进行提取和纯化,通过测定肌球蛋白在不同热变性温度下Ca2+-ATPase的变性速率常数(KD),考察了两种淡水鱼肌球蛋白热稳定性的季节变化。研究结果表明,两种鱼肌球蛋白Ca2+-ATPase的活性均显示夏季鱼>春季鱼>秋季鱼>冬季鱼。在35℃、40℃、45℃和50℃的热变性温度下,测定了两种鱼的肌球蛋白Ca2+-ATPase变性速率常数(KD),证明了肌球蛋白的热变性符合一级反应速度方程。经35℃热变性的肌球蛋白的KD值显示了冬季鱼约为夏季鱼的4倍,而秋季鱼和春季鱼介于冬季鱼和夏季鱼之间,且秋季鱼的KD值略低于冬季鱼,而春季鱼的KD值略高于夏季鱼。在40℃、45℃和50℃的热变性温度下,对各种肌球蛋白测得的KD值的变化趋势与上述结果相似。本研究证明了淡水鱼肌球蛋白的热稳定性夏季鱼明显优于冬季鱼,而春季鱼和秋季鱼分别与夏季鱼和冬季鱼的相似。更多还原

【Abstract】 In this study,myosins were prepared from fast skeletal muscles of grass carp(Ctenopharyngodon idellus) and silver carp(Hypophthalmichthys molitrix) seasonally acclimatized and collected in winter(January),spring(April),summer(August) and autumn(November).Seasonal changes in thermal stabilities of myosins from the two species of freshwater fish were examined by determining inactivation rate constants(KD) of Ca2+-ATPase.The results indicated that Ca2+-ATPase activities of myosins from the two species of freshwater fish showed the summer fish>the spring fish>the autumn fish>the winter fish.The KD values of Ca2+-ATPase of myosins incubated at 35,40,45 and 50 ℃ were measured,demonstrating thermal denaturation of myosin proceeds as the first-order reaction.The KD values for myosins incubated at 35 ℃ showed that the winter fish were about 4 times higher than those from the summer fish,whereas myosins from the autumn and spring fish showed KD values comparable to those of the winter and summer fish,respectively,and the former was slightly lower than the winter fish and the latter was slightly higher than the summer fish.Change tendency of the KD values of Ca2+-ATPase for myosins incubated at 40,45 and 50 ℃ was similar to those for myosins incubated at 35 ℃.These results demonstrated that thermal stabilities of myosins from freshwater fish seasonally acclimatized were different,namely the summer fish was significantly superior to the winter fish,whereas the spring and autumn fish had thermal stabilities similar to those of the summer and winter fish,respectively.更多还原