pH值对中国龙虾消化酶活力的影响

采用酶学分析方法研究了pH对中国龙虾胃蛋白酶、类胰蛋白酶、淀粉酶、纤维素酶和脂肪酶活力的影响。结果表明,在设定的pH范围内,中国龙虾各消化酶的活力均随着pH的升高呈现先升后降的变化趋势。其中,胃、肠、肝胰腺内胃蛋白酶最适pH均为2.2,类胰蛋白酶最适pH分别为8.8-9.2、8.4、8.8,淀粉酶最适pH分别为7.0、7.0、7.4,纤维素酶最适pH分别为4.2、4.2-4.6、5.4,脂肪酶最适pH分别为7.2-7.6、7.2、6.8-7.2。同时测得中国龙虾胃、肠、肝胰腺内的生理pH分别为5.33、6.93、6.60。中国龙虾的消化酶活力存在器官特异性。在最适pH下,胃蛋白酶活力顺序为胃>肠>肝胰腺,类胰蛋白酶、纤维素酶、脂肪酶的活力顺序均为肝胰腺>肠>胃,淀粉酶的活力顺序为肠>肝胰腺>胃。

Effects of pH on the activities of digestive enzymes in Panulirus stimpsoni

Effects of pH on the activities of five digestive enzymes(pepsin,tryptase,amylase,cellulase and lipase)in stomach,intestine and hepatopancreas of Panulirus stimpsoni were studied by means of enzyme analyses.The results showed that the activities of all digestive enzymes in Panulirus stimpsoni increased first and then decreased with pH increasing in the designed pH ranges.The optimum pH in stomach,intestine and hepatopancreas were all 2.2 for pepsin,8.8-9.2,8.4 and 8.8 respectively for tryptase,7.0,7.0 and 7.4 respectively for amylase,4.2,4.2-4.6 and 5.4 respectively for cellulase,and 7.2-7.6,7.2 and 6.8-7.2 respectively for lipase.The results indicate that pepsin and cellulase are conducive to acidic conditions,tryptase is conducive to alkaline conditions and amylase and lipase are conducive to neutral conditions.The physiological pH in stomach,intestine and hepatopancreas of Panulirus stimpsoni measured in our experiment were 5.33,6.93 and 6.60 respectively.This result indicates that pH in the digestive organs of Panulirus stimpsoni is weakly acidic.The activities of digestive enzymes in Panulirus stimpsoni have organic specificity.Under optimum pH,the activity of pepsin in different organs was in the order of stomach>intestine>hepatopancreas,the activities of tryptase,cellulose and lipase were hepatopancreas>intestine>stomach,while the activity of amylase was intestine>hepatopancreas>stomach.