链霉菌Strz-6木聚糖酶的纯化和固定化研究

Immobilization and purification for xylanase from Streptomyces sp.

链霉菌胞外木聚糖酶经过盐析、离子交换和分子筛层析纯化，粗酶液被纯化了32．5倍，比活力达498u/mg，活力回收46．6％。纯化后的酶固定在戊二醛交联的壳聚糖上，酶活回收率N42．8％。固定化酶的最适pH为6，0，最适温度为60℃，且固定化酶在65-75℃活力都较高。该酶的耐热性比较强，固定化酶热稳定性优于原酶；以木聚糖为底物，固定化酶的表观米氏常数为0．93×10^22g/L。

The extracellular xylanase from Streptomyces sp. Strz-6 was purified 32.5 times by salting out, ion-exchange and molecular sieve chromatography. The specific activity and recovery of purification xylanase were 498 u/mg and 46.6 % respectively. Purified xylanase was immobilized on the chitosan. The residual activity of immobilized was 42.8 %. The optimum pH of immobilized enzyme was pH 6.0. The optimum temperature of immobilized enzyme was 60℃. The thermal stability of immobilized enzyme was better than soluble enzyme at 65℃. The apparent Kin＇ of the immobilized enzyme was 0.83 × 10^-2g/L and the Km of soluble enzyme was 1.02 × 10^-2g/L with xylan as the substrate.