Properties of Aspergillus subolivaceus free and immobilized dextranase
Properties of Aspergillus subolivaceus free and immobilized dextranase
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DOI：
10.1007/s00217-011-1570-1
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发表时间：
2011-11-01
影响因子：
3.3
通讯作者：
Sherief, A. A.
中科院分区：
文献类型：
--
作者：
El-Tanash, A. B.;El-Baz, E.;Sherief, A. A.
采用包埋法和交联共价结合法将亚橄榄曲霉葡聚糖酶固定在几种载体上。以BSA为载体，交联剂固定化葡聚糖酶的酶活最高，固定化率为66.7%。固定化酶的最适pH由游离酶的pH 5.5移至pH 6.0。游离酶和固定化酶的最适反应温度均为60 ℃。热稳定性和pH稳定性通过固定化过程显著提高。固定化葡聚糖酶的Km（14.24 mg mL（-1））高于游离葡聚糖酶的Km（11.47 mg mL（-1）），而Vmax（2.80 U mug protein（-1））低于游离葡聚糖酶的Vmax（11.75 U mug protein（-1））。固定化酶经5.0次循环后仍能保持76%的催化活性。
Aspergillus subolivaceus dextranase is immobilized on several carriers by entrapment and covalent binding with cross-linking. Dextranase immobilized on BSA with a cross-linking agent shows the highest activity and considerable immobilization yield (66.7%). The optimum pH of the immobilized enzyme is shifted to pH 6.0 as compared with the free enzyme (pH 5.5). The optimum temperature of the reaction is resulted at 60 degrees C for both free and immobilized enzyme. Thermal and pH stability are significantly improved by the immobilization process. The calculated K-m of the immobilized dextranase (14.24 mg mL(-1)) is higher than that of the free dextranase (11.47 mg mL(-1)), while V-max of the immobilized enzyme (2.80 U mu g protein(-1)) is lower than that of the free dextranase (11.75 U mu g protein(-1)). The immobilized enzyme was able to retain 76% of the initial catalytic activity after 5.0 cycles.