TY - JOUR
T1 - Biosynthesis of glycyrrhetic acid 3-O-mono-β-d-glucuronide catalyzed by β-d-glucuronidase with enhanced bond selectivity in an ionic liquid/buffer biphasic system
AU - He, Dong Mei
AU - Kaleem, Imdad
AU - Qin, Si Ying
AU - Dai, Da Zhang
AU - Liu, Gui Yan
AU - Li, Chun
PY - 2010/12
Y1 - 2010/12
N2 - The bond selective hydrolysis of glycyrrhizin (GL) to glycyrrhetic acid 3-O-mono-β-d-glucuronide (GAMG) catalyzed by recombinant β-d-glucuronidase from Escherichia coli BL21 (PGUS-E) was successfully performed in an ionic liquid (IL)/buffer biphasic system. Five ILs were analyzed, however, a hydrophobic IL 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) showed the best biocompatibility with PGUS-E. An obvious enhancement in the initial reaction rate, substrate conversion, GAMG yield and chemical bond selectivity (Scb) was observed using 40% (v/v) [BMIM]PF6/buffer as the reaction medium when compared to the acetate buffer medium. Under the optimized conditions (pH 6.0, temperature 50°C, substrate concentration 6mM and shaking speed 200rpm), the initial reaction rate, the GAMG yield and the Scb reached 3.15mMh-1, 74.36% and 98.12%, respectively. The recyclability of [BMIM]PF6 was also studied and found to be reusable for five batches with high recovery percentage (≥92%). Furthermore, the desired product and byproduct were easily separated since they were distributed in different phases. Additionally, higher Vmax (3.14 versus 2.24mMh-1), lower apparent Km (1.21 versus 1.80mM) and Ea (25.97 versus 32.60kJmol-1) were achieved in [BMIM]PF6/buffer biphasic system than that in monophasic buffer system.
AB - The bond selective hydrolysis of glycyrrhizin (GL) to glycyrrhetic acid 3-O-mono-β-d-glucuronide (GAMG) catalyzed by recombinant β-d-glucuronidase from Escherichia coli BL21 (PGUS-E) was successfully performed in an ionic liquid (IL)/buffer biphasic system. Five ILs were analyzed, however, a hydrophobic IL 1-butyl-3-methylimidazolium hexafluorophosphate ([BMIM]PF6) showed the best biocompatibility with PGUS-E. An obvious enhancement in the initial reaction rate, substrate conversion, GAMG yield and chemical bond selectivity (Scb) was observed using 40% (v/v) [BMIM]PF6/buffer as the reaction medium when compared to the acetate buffer medium. Under the optimized conditions (pH 6.0, temperature 50°C, substrate concentration 6mM and shaking speed 200rpm), the initial reaction rate, the GAMG yield and the Scb reached 3.15mMh-1, 74.36% and 98.12%, respectively. The recyclability of [BMIM]PF6 was also studied and found to be reusable for five batches with high recovery percentage (≥92%). Furthermore, the desired product and byproduct were easily separated since they were distributed in different phases. Additionally, higher Vmax (3.14 versus 2.24mMh-1), lower apparent Km (1.21 versus 1.80mM) and Ea (25.97 versus 32.60kJmol-1) were achieved in [BMIM]PF6/buffer biphasic system than that in monophasic buffer system.
KW - Bond selectivity
KW - Glycyrrhetic acid 3-O-mono-β-d-glucuronide
KW - Glycyrrhizin
KW - Ionic liquid
KW - β-d-Glucuronidase
UR - http://www.scopus.com/inward/record.url?scp=78149499087&partnerID=8YFLogxK
U2 - 10.1016/j.procbio.2010.03.015
DO - 10.1016/j.procbio.2010.03.015
M3 - Article
AN - SCOPUS:78149499087
SN - 1359-5113
VL - 45
SP - 1916
EP - 1922
JO - Process Biochemistry
JF - Process Biochemistry
IS - 12
ER -