水／离子液体[BMIM]PF6两相体系中全细胞催化生成单葡萄糖醛酸基甘草次酸  

Biosynthesis of glycyrrhetic acid 3-O-mono-β-D-glucuronide by whole cell in ionic liquid/water biphasic system

作　　者：陈金燕[1] 邹树平[2] 何冬梅[1] 杨晓刚[3] 李春[1,3] 

机构地区：[1]石河子大学化学化工学院,新疆石河子832003 [2]浙江工业大学生物工程研究所,浙江杭州310014 [3]北京理工大学生命学院,北京100081

出　　处：《化工学报》2011年第11期3136-3142,共7页CIESC Journal

基　　金：国家自然科学基金项目(20976014);教育部博士点基金项目(20091101110036)~~

摘　　要：研究了水/离子液体两相体系中重组毕赤酵母Pichia pastoris GS115(r-PGUS-P)全细胞转化甘草酸(GL)生成单葡萄糖醛酸基甘草次酸(GAMG)的反应。确定最适反应体系为离子液体[BMIM]PF6/水(2∶8,体积比),最适缓冲液pH、反应温度、底物浓度和细胞加入量分别为5.4、45℃、6.0mmol.L-1和8.0g.L-1。在此条件下反应58h,产物GAMG得率和化学键选择性分别为69.6%和67.2%,与纯水相反应体系相比,分别提高了12.4%和12.61%。离子液体循环使用7次后,回收利用率为93.47%。产物GAMG和副产物甘草次酸(GA)在此两相体系中得到有效分离,为后续产物分离带来便利。Glycyrrhizin （GL）, the biologically active compounds of liquorice, can be hydrolysed to glycyrrhetic acid 3-O-mono-β-D-glucuronide （GAMG） by whole cells containing β-D-glucuronidase. GAMG is widely used in the pharmaceutical and food industries due to its stronger physiological functions, higher biological activity, more favorable sweetness, and lower caloric value as compared with GL. The recombinant Pichia pastoris （r-PGUS-P） designated in this work expressing β-D-glucuronidase, was used as a whole-cell biocatalyst catalyzing GL to GAMG in non-aqueous solvents systems. The results showed that r-PGUS-P gave the highest yield of GAMG in 1-butyl-3-methylimidazolium hexafluorophosphate （ [BMIM] PF6 ）/water （2 ： 8, vol） biphasic system. The optimal conditions of this reaction were determined as follows： optimum pH, substrate concentration, temperature and cell content were 5.4, 6.0 mmol- L 1, 45℃, and 8.0 g . L-1, respectively. Under these optimized conditions, 69.6% yield of GAMG and 67.2% of the chemical bond selectivity was achieved after 58 h reaction time, increase by 12.4% and 12.61%, respectively against aqueous phase. Simultaneously, the ionic liquid [BMIM]PF6 also remained at higher recovery percentage of about 93.47% during repeated use for Especially, product GAMG and byproduct glycyrrhetinic acid （GA） got separated automatically that brought convenience for the separation and purification of GAMG. reaction biphasie cycles. system

关 键 词：离子液体 全细胞 甘草酸 β-D葡萄糖醛酸苷酶 单葡萄糖醛酸基甘草次酸 

分 类 号：Q814.9[生物学—生物工程]