粪肠球菌埃萨维葡聚糖蔗糖酶的共价固定化及葡聚糖合成
Covalent immobilization of Enterococcus faecalis Esawy dextransucrase and dextran synthesis.
作者信息
Hashem Amal M, Gamal Amira A, Hassan Mohamed E, Hassanein Naziha M, Esawy Mona A
机构信息
Department of Chemistry of Microbial and Natural Products, National Research Centre (NRC), Dokki, Cairo, Egypt.
Center of Excellence, Encapsulation & Nanobiotechnology Group, National Research Center, Egypt.
出版信息
Int J Biol Macromol. 2016 Jan;82:905-12. doi: 10.1016/j.ijbiomac.2015.09.076. Epub 2015 Oct 3.
Enterococcus faecalis Esawy dextransucrase was immobilized in Fe(3+)-cross-linked alginate/carboxymethyl cellulose (AC) beads. The gel beads were modified with polyethylenimine (PEI) followed by glutaraldehyde (GA) to form Fe(3+) (ACPG) beads. Fe(3+) (ACPG) was characterized using FTIR and DSC techniques. GA activated beads showed new two peaks. The first was at 1,717 cm(-1) which refers to (CO) group of a free aldehyde end of glutaraldehyde, and another peak was at 1,660 cm(-1) referring to (CN) group. The immobilization process improved the optimum temperature from 35 to 45°C. The immobilized enzyme showed its optimum activity in wide pH range (4.5-5.4) compared to pH 5.4 in case of free form. Also, the immobilization process improved the thermal and pH enzyme stability to great extent. Reusability test proved that the enzyme activity retained 60% after 15 batch reactions. Immobilized enzyme was applied successfully in the synthesis of oligosaccharides and different molecular weights of dextran.
粪肠球菌埃萨维葡聚糖蔗糖酶被固定在Fe(3+)交联的海藻酸钠/羧甲基纤维素（AC）珠粒中。凝胶珠粒先用聚乙烯亚胺（PEI）修饰，然后用戊二醛（GA）修饰，形成Fe(3+)（ACPG）珠粒。采用傅里叶变换红外光谱（FTIR）和差示扫描量热法（DSC）技术对Fe(3+)（ACPG）进行了表征。经GA活化的珠粒出现了两个新峰。第一个峰位于1717 cm(-1)处，代表戊二醛游离醛端的（CO）基团，另一个峰位于1660 cm(-1)处，代表（CN）基团。固定化过程将最适温度从35℃提高到了45℃。与游离形式在pH 5.4时相比，固定化酶在较宽的pH范围（4.5 - 5.4）内表现出最佳活性。此外，固定化过程在很大程度上提高了酶的热稳定性和pH稳定性。重复使用性测试证明，经过15批次反应后，酶活性保留了60%。固定化酶成功应用于寡糖和不同分子量葡聚糖的合成。
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