Jung Kyung-Hwan
Division of Food and Biotechnology, Chungju National University, Chungju, Chungbuk 380-702, Korea.
J Microbiol Biotechnol. 2008 Mar;18(3):434-42.
We observed that an inclusion body (IB) of recombinant beta-galactosidase that was produced by the araBAD promoter system in Escherichia coli (E. coli) showed enzyme activity. In order to improve its activity, the lowering of the transcription rate of the beta-galactosidase structural gene was attempted through competition between an inducer (L-arabinose) and an inducer analog (D-fucose). In the deep-well microtiter plate culture and lab-scale fermentor culture, it was demonstrated that the addition of D-fucose caused an improvement in specific beta-galactosidase production, although beta-galactosidase was produced as an IB. In particular, the addition of D-fucose after induction led to an increase in the specific activity of beta-galactosidase IB. Finally, we confirmed that the addition of D-fucose after induction caused changes in the structure of beta-galactosidase IB, with higher enzyme activity. Based on these results, we expect that an improved enzyme IB will be used as a biocatalyst of the enzyme bioprocess, because an enzyme IB can be purified easily and has physical durability.
我们观察到，由阿拉伯糖操纵子（araBAD）启动子系统在大肠杆菌（E. coli）中产生的重组β-半乳糖苷酶的包涵体（IB）具有酶活性。为了提高其活性，尝试通过诱导剂（L-阿拉伯糖）和诱导剂类似物（D-岩藻糖）之间的竞争来降低β-半乳糖苷酶结构基因的转录速率。在深孔微量滴定板培养和实验室规模的发酵罐培养中，结果表明，尽管β-半乳糖苷酶是以包涵体形式产生的，但添加D-岩藻糖可提高β-半乳糖苷酶的比产量。特别是，诱导后添加D-岩藻糖导致β-半乳糖苷酶包涵体的比活性增加。最后，我们证实诱导后添加D-岩藻糖会导致β-半乳糖苷酶包涵体结构发生变化，酶活性更高。基于这些结果，我们期望改进后的酶包涵体将用作酶生物过程的生物催化剂，因为酶包涵体易于纯化且具有物理稳定性。
