[Enzymatic glycosylation of 4'-demethylepipodophyllotoxin].

The glycosides of 4'-demethylepipodophyllotoxin (DMEP) possess various pharmacological activities; however, the chemical synthesis of these glycosides faces challenges in regioselectivity, stereoselectivity, and the protection and de-protection of functional groups. In this work, a novel glycosyltransferase (GT) gene AbGT5 from Aloe barbadensis was successfully cloned, heterogeneously expressed and purified. Recombinant AbGT5 was able to catalyze the glycosylation of DMEP and the glycosylated product, which was separated from the preparative scale reaction, was characterized as DMEP 4'-O-ß-D-glucoside via MS, 1H-NMR, 13C-NMR, HSQC and HMBC. According to the investigations of enzyme properties, AbGT5 show the highest activity around 20 ℃ in the buffer of pH 9.0, and it was independent of divalent metal ions. Under the optimum conditions, the conversion rate of DMEP can reach 80%. Above all, in this work the enzymatic glycosylation of DMEP was achieved with high efficiency by the novel GT AbGT5.

Enzymatic glycosylation of 4'-demethylepipodophyllotoxin / 中国中药杂志

The glycosides of 4'-demethylepipodophyllotoxin (DMEP) possess various pharmacological activities; however, the chemical synthesis of these glycosides faces challenges in regioselectivity, stereoselectivity, and the protection and de-protection of functional groups. In this work, a novel glycosyltransferase (GT) gene AbGT5 from Aloe barbadensis was successfully cloned, heterogeneously expressed and purified. Recombinant AbGT5 was able to catalyze the glycosylation of DMEP and the glycosylated product, which was separated from the preparative scale reaction, was characterized as DMEP 4'-O-β-D-glucoside via MS, 1H-NMR, 13C-NMR, HSQC and HMBC. According to the investigations of enzyme properties, AbGT5 show the highest activity around 20 ℃ in the buffer of pH 9.0, and it was independent of divalent metal ions. Under the optimum conditions, the conversion rate of DMEP can reach 80%. Above all, in this work the enzymatic glycosylation of DMEP was achieved with high efficiency by the novel GT AbGT5.

Expression,purification and cleavage activity analysis of self-processed recombinant MBP-HRV 3C fusion protease in E.coli expression system / 国际检验医学杂志

Objective To obtain a novel tool-enzyme for genetic engineering with good solubility,strong specificity of enzyme digestion and maintaining the enzyme activity at low temperature by using E.coli expression system to express self-processed re-combinant MBP-HRV 3C fusion protease.Methods The cDNA encoding HRV 3C protease was cloned into pRSF-Duet vector.The recombinant plasmid was transferred into E.coli BL21 (DE3)for expression.HRV 3C protease was obtained through Nichol col-umn affinity purification.The cleavage activity of HRV 3C protease was determined by in vivo experiment.Results HRV 3C prote-ase was highly expressed in E.coli expression system,and the obtained HRV 3C protease could recognize and digest HRV 3C site. Conclusion A novel tool-enzyme for genetic engineering is obtained.