Liu Ya-Li, Jiang Shu, Ke Zu-Min, Wu Hai-Shui, Chi Cheng-Wu, Guo Zhan-Yun
Zhejiang Feng'an Biopharmaceutical, Xianju 317300, China.
Carbohydr Res. 2009 Apr 21;344(6):815-9. doi: 10.1016/j.carres.2009.01.027. Epub 2009 Feb 11.
Recently, considerable attention has been focused on chitosan oligosaccharides (COSs) due to their various biological activities. COSs can be prepared by enzymatic degradation of chitosan, which is the deacetylation product of chitin, one of the most abundant biopolymers in nature. In the current study, we recombinantly expressed a chitosanase and used it for COS preparation. A bacillus-derived GH8 family chitosanase with a 6xHis tag fused at its N-terminal was expressed in the Escherichia coli strain BL21(DE3) as a soluble and active form. Its expression level could be as high as 500 mg/L. Enzymatic activity could reach approximately 140,000 U/L under our assay conditions. The recombinant chitosanase could be purified essentially to homogeneity by immobilized metal-ion affinity chromatography. The enzyme could efficiently convert chitosan into monomer-free COS: 1g of enzyme could hydrolyze about 100 kg of chitosan. Our present work has provided a cheap chitosanase for large-scale COS production in industry.
近年来，壳寡糖（COSs）因其多种生物活性而备受关注。壳寡糖可通过壳聚糖的酶促降解制备，壳聚糖是几丁质的脱乙酰产物，几丁质是自然界中最丰富的生物聚合物之一。在本研究中，我们重组表达了一种壳聚糖酶并将其用于制备壳寡糖。一种来源于芽孢杆菌的GH8家族壳聚糖酶，其N端融合有6xHis标签，在大肠杆菌BL21(DE3)菌株中以可溶且有活性的形式表达。其表达水平可达500 mg/L。在我们的测定条件下，酶活性可达约140,000 U/L。重组壳聚糖酶可通过固定化金属离子亲和色谱基本上纯化至同质。该酶可有效地将壳聚糖转化为无单体的壳寡糖：1克酶可水解约100千克壳聚糖。我们目前的工作为工业大规模生产壳寡糖提供了一种廉价的壳聚糖酶。
