温度和pH对澳洲宝石鱼消化酶活性的影响

The effects of temperature and pH on activities of digestive enzymes in jade perch(Scortum barcoo) in Australia

通过改变酶反应温度和pH，分析了澳洲宝石鱼Scortum barcoo淀粉酶、蛋白酶和脂肪酶活性的变化。结果表明，澳洲宝石鱼肝胰脏、肠道、胃淀粉酶的最适pH均为6．2；肝胰脏、肠道蛋白酶的最适pH分别为7．5、7．0～7．5，胃蛋白酶的最适pH为2．0。说明淀粉酶在中性偏酸性时活性最高，肝胰脏、肠道蛋白酶在中性偏碱性时活性最高，而胃蛋白酶在强酸性时活性最高。肝胰脏、肠道、胃的淀粉酶的最适温度均为30℃，脂肪酶的最适温度分别为柏、35、35℃，蛋白酶的最适温度分别为50、50、40℃。在一定温度和pH范围内，3种消化酶的活力均呈先上升后下降的趋势，并在各自最适的温度下，3种消化酶比活力的大小均为肠道〉胃〉肝胰脏。

The effect of different temperature and pH on activities of three digestive enzymes in jade perch Scortum barcoo were examed. The optimum pH value for amylase in liver, intestine and the stomach were all 6.2 at water temperature of 25℃ The optimum pH value for protease of liver, intestine were all 7.0 - 7.5, and 2.0 and 6.5 in stomach at water temperature of 40℃ The results indicated that amylase was conductive to weak acidic condition, and protease in liver and intestine were conductive to weak alkaline condition while the protease in stomach was conductive to acidic condition. The optimum temperature in amylase of the liver, intestine and stomach were all 30℃ when the reaction pH value was 6.9. The optimum temperature for protease were 50,50,40℃ and for lipase were 40,35,35℃ respectively pH value of 7.5. The results indicated that the optimum temperature of the three digestive enzymes in liver, intestine and stomach were higher than the temperature for growth. The activities of amylase,lipase and protease increased, then decreased within the test temperature range. All the activity of three digestive enzymes was in an order of from strong to weak： intestine, liver, and stomach at the most favorable temperature.