Bhatia Yukti, Mishra Saroi, Bisaria Virendra S
Department of Biochemical Engineering and Biotechnology, Indian Institute of Technology, Delhi, Hauz Khas, New Delhi.
Appl Biochem Biotechnol. 2002 Jul-Dec;102-103(1-6):367-79. doi: 10.1385/abab:102-103:1-6:367.
The hydrolysis and biosynthetic reactions of partially purified Pichia etchellsii beta-glucosidase II from recombinant Escherichia coli pBG22:JM109 are described. With 167 mmol/L of initial glucose, the products of synthetic reactions, glucobiose and glucotriose, accumulated to 18 and 6 mmol/L, respectively. In transglycosylation reactions with 79 mmol/L of initial cellobiose, glucotriose and glucopentaose were obtained at 4.5 and 2 mmol/L, respectively. The effects of incubation time and substrate concentration were studied on the yield of synthesized oligosaccharides. In a reaction time of 24 h with 468 mmol/L of initial cellobiose, glucotriose and glucopentaose levels of 21.6 and 6.6 mmol/L, respectively, were obtained. The addition of dimethyl sulfoxide (DMSO) further increased the yields of the products by 10%. Detailed kinetic analysis indicated a significant (about twofold) increase in Vmax/KM of synthetic reactions in the presence of DMSO. A study of other disaccharides in transglycosylation reactions indicated biosynthetic activity in the order of sophorose > gentiobiose > cellobiose.
描述了从重组大肠杆菌pBG22:JM109中部分纯化的埃氏毕赤酵母β-葡萄糖苷酶II的水解和生物合成反应。初始葡萄糖浓度为167 mmol/L时，合成反应产物葡萄糖二糖和葡萄糖三糖分别积累至18 mmol/L和6 mmol/L。在初始纤维二糖浓度为79 mmol/L的转糖基化反应中，分别获得了浓度为4.5 mmol/L和2 mmol/L的葡萄糖三糖和葡萄糖五糖。研究了孵育时间和底物浓度对合成寡糖产量的影响。在初始纤维二糖浓度为468 mmol/L的24小时反应中，分别获得了浓度为21.6 mmol/L和6.6 mmol/L的葡萄糖三糖和葡萄糖五糖。添加二甲基亚砜（DMSO）使产物产量进一步提高了10%。详细的动力学分析表明，在DMSO存在下，合成反应的Vmax/KM显著增加（约两倍）。对转糖基化反应中其他二糖的研究表明，生物合成活性顺序为槐糖>龙胆二糖>纤维二糖。
