温度和pH对异育银鲫消化酶稳定性及其活力的影响

Effects of temperature and pH on stability and activity of digestive enzymes of gibei carp Carassius auratus gibelio

从酶学分析的角度研究温度、pH值对异育银鲫Carassius auratus gibelio消化酶稳定性及其活力的影响。结果显示,蛋白酶、淀粉酶和纤维素酶在30～50℃分别保留相对酶活力达82%、87%和90%以上,蛋白酶相对酶活力在pH值6.0～9.2达71%以上,淀粉酶相对酶活力在pH 5.8～9.0达75%以上,纤维素酶在pH值3.6～7.0保留相对酶活力达70%以上,在不同温度条件下,蛋白酶活性顺序为前肠>后肠>中肠,淀粉酶活性顺序为中肠>前肠>后肠,纤维素酶活性顺序为后肠>中肠>前肠。蛋白酶、淀粉酶和纤维素酶获得较大活性的部位分别分布在前肠、中肠和后肠,其最适温度分别为25～30℃、35～40℃和20～25℃。在不同的pH值条件下,蛋白酶活性顺序为中肠>后肠>前肠,淀粉酶活性顺序为后肠>中肠>前肠,纤维素酶活性顺序为后肠>前肠>中肠。蛋白酶、淀粉酶和纤维素酶获得较大活性的部位分别分布在中肠、后肠和后肠,其最适pH值分别为7.6～8.4、6.4和3.6～4.8。表明消化酶对热和pH值具有一定的稳定性;蛋白酶、淀粉酶在适宜条件下具有较大酶活力。

The stability and activity of digestive enzymes of gibel carp Carassius auratus gibelio at different temperatures and pH values were examined by means of enzymology analysis. It was found that the relative enzyme activity of protease, amylase and cellulose were above 82%, 87% and 90%, respectively at30-50℃. Relative enzyme activity of protease was above 71% at pH 6.0-9.2, that of amylase was above 75% at pH 5.8-9.0, and that of cellulase was above 70% at pH 3.6-7.0. At different temperatures, the ranking of protease activity was foregut〉hindgut〉midgut, that of amylase activity was midgut〉foregut〉hindgut, and that of cellulase activity was hindgut〉midgut〉foregut. Higher enzyme activity was found for protease, amylase and cellulase in foregut, midgut and hindgut, respectively; and the optimum temperatures for these enzymes were 25-30 ℃, 35-40℃ and 20-25℃, respectively. At different pH values, the ranking of protease activity was midgut〉hindgut〉foregut, that of amylase activity was hindgut〉midgut〉foregut, and that of cellulase activity was hindgut〉 foregut〉midgut. Higher enzyme activity of protease, amylase and cellulase was found in midgut, hindgut and hindgut, respectively; and the optimum pH values were 7.6-8.4 for protease, 6.4 for amylase and 3.6-4. 8 for cellulase. This study revealed that the digestive enzymes were stable at a range of temperatures and pH values; and protease and amylase showed higher enzyme activity at optimum temperatures and pH values.