球形交联壳聚糖固定化果胶酶的制备及特性研究

Study on Preparation and Properties of Immobilized Pectinase from Aspergillus niger on Globular Cross-linked Chitosan

研究了球形交联壳聚糖固定化果胶酶的制备及其特性。结果表明:壳聚糖溶液浓度为2.0%,凝结液组成为15%NaOH∶75%乙醇=4∶1(体积比),以5.0%戊二醛交联6 h,可制得交联壳聚糖球载体;1 g载体固定10 mg的果胶酶,载体先与酶液缓慢振荡混合40 min后,在固定化体系(pH 3.4,4℃)中固定反应12 h,该条件下制得的固定化酶强度大,酶活力回收率高达91.45%;固定化果胶酶的最适温度45℃,最适pH 3.4,Kmapp值9.97 mg/mL;固定化酶的酸碱稳定性与温度稳定性均得到提高,连续使用7次后固定化酶活力还剩余53.74%。

The preparation and properties of immobilized pectinase from Aspergillus niger on globular cross-linked chitosan were investigated. When the concentration of chitosan solution was 2.0%, the composition of coagulation liquid was 15% NaOH ： 40% ethanol=4 ： 1 （in Volume）, and after being cross-linked with 5.0 % glutaraldehyde for 6 hours, globular cross-linked chitosan carrier was successfully made. The optimum conditions for immobilization were investigated, and the results showed that, with ten milligramme pectinase for one gramme carrier, after 40 minute oscillation and mixture of enzyme and carrier, the process time was 12 h at 4 ℃ under pH 3.4 of reaction medium and the recovery rate of enzyme activity was 91.45%, while the strength of immobilized enzyme remained strong enough. The optimum pH and optimum temperature of immobilized pectinase for the hydrolysis of pectin were determined to be pH 3.4 and 45 ℃, respectively. The apparent Michaelis constant of immobilized pectinase Km^App equaled to 9.97 mg/mL. The stability of immobilized enzyme to pH and temperature was greater than that of the natural enzyme. The recovery activity of immobilized pectinase was more than 53. 74% after being repeated seven times.