Department of Chemical and Biological Engineering, Hanbat National University, Daejeon, 34158, Republic of Korea.
Department of Chemistry and Biochemistry, South Dakota State University, Brookings, SD, 57007, USA.
Biotechnol Lett. 2020 May;42(5):845-852. doi: 10.1007/s10529-020-02829-w. Epub 2020 Feb 1.
Sodium dodecyl sulfate (SDS)-chitosan hydrogels have been employed for adsorption of anionic dyes and metallic substances. Two mutant forms of Thermoanaerobacter ethanolicus alcohol dehydrogenase (TeSADH) were used as model enzymes to develop a novel enzyme immobilization technique employing newly formulated porous chitosan hydrogels.
The enzyme immobilized on chitosan hydrogel capsules formed by 5 g/l SDS gelation and subsequent treatment with 0.05 M NaOH was 28-35% higher in NADPH production than that formed by 20 g/l SDS gelation only under the same conditions. A 48-h asymmetric biphasic reduction of acetophenone with immobilized TeSADH enzyme at 50 °C showed 68% increase in (R)-1-phenylethanol production than the free enzyme. Compared to the free enzyme which denatured and lost its activity at 80 °C, the immobilized enzyme retained about 25% of its initial activity after 2-h incubation.
In contrast to the conventional chitosan hydrogel which suffers thermal and operational stability, the newly formulated porous chitosan hydrogel capsules have excellent enzyme loading efficiency and stable at harsh temperatures. Especially, this newly developed enzyme immobilization method would be applicable for food processing.
十二烷基硫酸钠（SDS）-壳聚糖水凝胶已被用于吸附阴离子染料和金属物质。两种突变形式的热厌氧菌乙醇脱氢酶（TeSADH）被用作模型酶，开发了一种新的酶固定化技术，采用新配方的多孔壳聚糖水凝胶。
在相同条件下，用 5 g/L SDS 凝胶化和随后用 0.05 M NaOH 处理形成的壳聚糖水凝胶胶囊中固定化的酶，与仅用 20 g/L SDS 凝胶化形成的酶相比，NADPH 的产生量提高了 28-35%。在 50°C 下，用固定化 TeSADH 酶进行 48 小时不对称双相还原苯乙酮，（R）-1-苯乙醇的产量比游离酶增加了 68%。与在 80°C 下变性失活的游离酶相比，固定化酶在孵育 2 小时后仍保留约 25%的初始活性。
与传统的热和操作稳定性差的壳聚糖水凝胶相比，新配方的多孔壳聚糖水凝胶胶囊具有优异的酶负载效率，在苛刻的温度下稳定。特别是，这种新开发的酶固定化方法将适用于食品加工。
