鲶鱼鱼鳃中血管紧张素转换酶类似酶的性质研究

Characterization of angiotensin converting-like enzyme from gills of catfish

以鲶鱼的鱼鳃为原料,用硫酸铵盐析法提取一种血管紧张素转换类似酶,采用反相高效液相色谱法对温度、pH、金属离子、抑制剂和米氏常数等酶学性质进行了研究。结果显示：温度对蛋白酶活性的影响非常明显,最适反应温度是40℃,在20~40℃之间稳定性较好;最适pH为9、pH8~11之间有较好的稳定性。Na＋对蛋白酶有一定促进作用,Cu2＋和K＋对蛋白酶有强烈抑制作用。卡托普利对蛋白酶活性有强烈抑制作用。以马尿酸-组氨酰-亮氨酸为底物,在pH9,40℃时测得Km值为0.18 mmol/L,Vmax是1.57 mmol/min。

Angiotensin converting-like enzyme was purified from catfish gills by ammonium sulfate precipitation and the enzymatic properties were studied by RP-HPLC. The result shows that： the enzyme was stable between 20~40 ℃ and extremely stable in the pH range 8~11. The optimal temperature and pH for the enzyme activity was 40 ℃ and 9, respectively. Further studies showed that the enzyme activity was increased by Na＋ and rapidly decreased by K＋, Cu2＋（1 mmol/L）. The activity was inhibited by Captopril（1 mmol/L）. Using hippuryl-L-His-Leu as substrate, under the pH 9, 40 ℃, Km value was 0.18 mmol/L and Vmax was 1.57 mmol/min.