School of Pharmacy, Jiangsu University, Zhenjiang, 212013, People's Republic of China.
College of Petroleum and Chemical Engineering, Qinzhou, 535100, People's Republic of China.
Bioprocess Biosyst Eng. 2022 Feb;45(2):353-364. doi: 10.1007/s00449-021-02665-w. Epub 2021 Nov 19.
The combined cross-linked enzyme aggregates (combi-CLEAs) containing galactitol dehydrogenase (Gdh) and NADH oxidase (Nox) were prepared for L-tagatose synthesis. To prevent the excess consumption of cofactor, Nox in the combi-CLEAs was used to in situ regenerate NAD. In the immobilization process, ammonia sulfate and glutaraldehyde were used as the precipitant and cross-linking reagent, respectively. The preparation conditions were optimized as follows: 60% ammonium sulfate, 1:1 (molar ratio) of Gdh to Nox, 20:1 (molar ratio) of protein to glutaraldehyde, and 6 h of cross-linking time at 35 °C. Under these conditions, the activity of the combi-CLEAs was 210 U g. The combi-CLEAs exhibited higher thermostability and preserved 51.5% of the original activity after eight cycles of reuses at 45 °C. The combi-CLEAs were utilized for the preparation of L-tagatose without by-products. Therefore, the combi-CLEAs have the industrial potential for the bioconversion of galactitol to L-tagatose.
用于 L-塔格糖合成的含有半乳糖醇脱氢酶（Gdh）和烟酰胺腺嘌呤二核苷酸氧化酶（Nox）的交联酶聚集体（CLEAs）被制备。为了防止辅助因子的过度消耗，在原位使用 Nox 将 NAD 再生。在固定化过程中，硫酸铵和戊二醛分别用作沉淀剂和交联剂。优化了制备条件如下：60%硫酸铵，Gdh 与 Nox 的摩尔比为 1:1，蛋白质与戊二醛的摩尔比为 20:1，交联时间为 35°C 下 6 小时。在此条件下，组合 CLEAs 的活性为 210 U g。组合 CLEAs 表现出更高的热稳定性，在 45°C 下重复使用 8 次后，仍保留了原始活性的 51.5%。组合 CLEAs 用于制备无副产物的 L-塔格糖。因此，组合 CLEAs 具有将半乳糖醇生物转化为 L-塔格糖的工业潜力。
