野生棘胸蛙消化器官蛋白酶的分布及酶活力

Distribution and Activity of Protease in Digestive Organs of Wild Giant Spiny Frog, Quasipaa spinosa

本研究在不同p H和温度条件下以离体方式对野生棘胸蛙(Quasipaa spinosa)不同消化器官的蛋白酶活力进行了分析。结果表明,食道、胃、胰的蛋白酶活力受到酶体系p H的显著影响(P<0.05),且随p H升高呈现典型的单峰型活力曲线。食道和胃的蛋白酶活力在p H为1.5时达到峰值,胰的酶活力在p H为9.6时达到峰值,而肠道酶活力在p H为7.4时达到峰值。各消化器官蛋白酶活力具有明显的温度依赖性(P<0.05),酶活力随温度升高也均呈典型的单峰型活力曲线,不同消化器官的最大酶活力温度分别为,食道50℃、胃50℃、胰45℃、前肠45℃、后肠45℃、直肠45℃。在最大酶活力的p H和30℃条件下,各消化器官蛋白酶活力由高到低依次为胰、食道、胃、直肠、前肠、后肠。由此可见,蛋白酶在棘胸蛙消化系统的分布具有明确的规律性,且不同来源的蛋白酶需要在特定p H和温度下才能表现出最大的反应活性。

This study investigated protease activities in different digestive organs of wild giant spiny frog （Quasipaa spinosa） in the range ofpH 0.5 to 10.0 at 30℃ and reaction temperature 15 to 60℃ at optimum pH in vitro. The protease activity was measured using the Folin-phenol method. The data were statistically analyzed by One-way ANOVA and LSD. The results showed that pH could affect protease activities of esophagus, stomach and pancreas significantly （P 〈 0.05）, and their dynamic curves of protease activities were typically unimodal with increasing pH （Fig. 1）.The protease activities of esophagus, stomach, pancreas and intestine were maximal at pH 1.5, 1.5, 9.6 and 7.4, respectively. The protease activities of digestive organs showed an obvious temperature dependence （P 〈 0.05）, and the curves were also typically unimodal （Fig. 2）. The protease activities of esophagus, stomach, pancreas, foregut, hindgut and rectum attained maximum value at temperature 50℃, 50℃, 45℃, 45℃, 45℃ and 45℃, respectively. Under the conditions of 30℃ and optimal pH mentioned above, digestive organs were arranged in order of descending protease activities： pancreas, esophagus, stomach, rectum, foregut and hindgut. In conclusion, there obviously exists a regular protease distribution in digestive system of this species, and the enzymes from different organs can show maximal activities at specific pH values and temperatures.