两相体系中β-葡萄糖苷酶催化栀子苷水解制备京尼平

京尼平是一种天然生物交联剂，且具有多种生理活性。本文以β-葡萄糖苷酶催化栀子苷水解制备京尼平为目标体系，证明了京尼平对β-D-葡萄糖苷酶具有竞争性抑制作用；考察了β-D-葡萄糖苷酶在不同有机相-水体系中的稳定性，发现其在正辛醇-水、正己醇-水体系中的稳定性均较好；测定了栀子苷在正辛醇-水和正己醇-水体系中的分配系数k_{D，gardenoside}分别为0.17和0.76，而京尼平的分配系数k_D，genipin为42.57和37.75；分别在水、正辛醇-水和正己醇-水体系中进行栀子苷水解制备京尼平的反应，当底物浓度为0.25 μmol·ml^-1时京尼平收率分别为89.17%、93.96%、90.16%；进一步提高底物浓度为2.0 μmol·ml^-1时，正辛醇-水体系中京尼平收率高达91.9%，较水相体系（79.7%）提高了12.2%。本文的研究结果证明了采用正辛醇-水两相反应体系可部分解除产物抑制，提高产物收率，并简化后续的产物分离。

Biosynthesis of genipin from gardenoside catalyzed by β-glucosidase in two-phase medium

Genipin is an important bio-crosslinking agent with multiple physiological activities. In this paper, the competitive inhibition for activity of β-glucosidase by genipin was demonstrated. The stabilities of β-glucosidase in different organic solvents were investigated. Stability of β-glucosidase was satisfactory in the octanol-water and hexanol-water medium. The partition coefficients for gardenoside in the octanol-water and hexanol-water system were 0.17 and 0.76, while those for genipin were 42.57 and 37.75 respectively. The process for preparation of genipin was carried out in water, octanol-water and hexanol-water respectively, while gardenoside concentration was 0.25 μmol·ml^-1. The obtained genipin yields were 89.17%, 93.96% and 90.16% respectively. Furthermore, the effect of gardenoside concentration on genipin yield was also investigated. While in the octanol-water system, conversion rate of genipin was as high as 91.9% at the gardenoside concentration of 2.0 μmol·ml^-1, an increase of 12.2% compared to that in water. Using the octanol-water medium was helpful for partially eliminating product inhibition, improving genipin yield and simplifying product recovery.