胃蛋白酶催化壳聚糖降解的特性研究

STUDIES ON THE HYDROLYSIS OF CHITOSAN BY PORCINE PEPSIN

采用粘度测定法和还原糖测定法 ,研究了温度、p H值、反应时间、底物浓度、金属离子及壳聚糖的脱乙酰化度对胃蛋白酶降解活性的影响 ,确定了以壳聚糖为底物的猪胃蛋白酶的一些催化特性 :最适温度为 70℃ ,最适 p H值为 5.0 ,米氏常数 Km为 8.94× 1 0 -3 g· m L-1,一定浓度的 Ca2 + ,Cu2 + ,Ba2 + ,Mn2 +抑制该酶的活性 .结果表明 :随着壳聚糖脱乙酰化度的提高 ,胃蛋白酶活性降低 .

The effects of reaction temperature, pH, substrate and enzyme concentration, some metal ions and the deacetylation degree of chitosan on the hydrolytic velocity of chitosan by porcine pepsin were investigated. The viscosity of chitosan solution was decreased quickly at the catalysis of pepsin. The optimum temperature and optimum pH were 70 ℃ and 5.0 respectively, and the K m value for chitosan was 8.94×10 -3 g·mL -1 . Ca 2+ , Mn 2+ , Cu 2+ , Ba 2+ were inhabitors, while ICH 2COOH activated the acti vity of pepsin. The results showed that the activity of pepsin was reduced while the degree of deacetylation of chitosan raised.