pH和温度对黄姑鱼主要消化酶活力的影响

Effects of pH and Temperature on the Main Digestive Enzyme Activities of Nibea albiflora(Richardson)

采用酶学分析的方法,研究了在不同pH和温度下离体黄姑鱼蛋白酶、淀粉酶、脂肪酶的活性变化。结果表明:pH和温度对黄姑鱼主要消化道各部位消化酶活力多数有显著影响(P<0.05),在黄姑鱼前肠、中肠、后肠、胃、肝胰脏5个部位,蛋白酶的最适pH分别为6.4、7.8、7.8、2.2、6.4,淀粉酶最适pH分别为5.0、7.8、7.8、6.4、5.0,脂肪酶的最适pH分别为5.0、6.4、7.8、3.6、5.0;在最适pH条件下,前肠、中肠、后肠、胃、肝胰脏中蛋白酶的最适温度均为40℃左右,淀粉酶的最适温度除肝胰脏中为40℃外,其他部位均为30℃,脂肪酶的最适温度均为40℃。蛋白酶活力在pH 6.4、37℃时达到最大值1 606.576±83.457 U,淀粉酶活性在pH 6.4、37℃时达到最大值188.086±17.538 U,脂肪酶在pH 5.0、40℃时达到最大值34.247±1.926 U。

Activities of digestive enzyme reflect the digestive level of Nibea albiflora（Richardson） to different nutritional ingredients,any changes in ambient factors would affect the activity of a digestive enzyme.Studying different ambient factors on the digestive enzymes in the N.albiflora is important for understanding the behavior of the enzymes.Among ambient factors,temperature and pH are the most two important affecting factors.Enzyme activities were analyzed including protease amylase and lipase by the enzyme analytical methods.The results showed that temperature and pH had notable effects on the activities of digestive enzymes in each part of the digestive tract of N.albiflora（P0.05）.The optimum pH value for protease were 6.4,7.8,7.8,2.2 and 6.4 in foregut,midgut,hindgut,stomach and hepatopancreas respectively,the optimum pH lipase for amylase was 5.0,7.8,7.8,6.4 and 5.0,respectively and that for lipase was 5.0,6.4,7.8,3.6 and 5.0 respectively.The optimum temperature for protease all were 40 ℃ at the optimum pH value;the optimum temperature for amylase was 40 ℃ in hepatopancreas,30 ℃ in the other organs;the optimum temperature for lipase all were 40 ℃.The maximal protease activity was 1 606.576± 83.457 U at pH 6.4 and 37 ℃;the maximal amylase activity was 188.086±17.538 U at pH 6.4 and 37 ℃;The maximal protease activity was 34.247±1.926 U at pH 5.0 and 40 ℃.