Chang Kyung Hoon, Jo Mi Na, Kim Kee-Tae, Paik Hyun-Dong
Division of Animal Life Science, Konkuk University, Seoul 143-701, Korea.
Bio/Molecular Informatics Center, Konkuk University, Seoul 143-701, Korea.
Int J Mol Sci. 2012;13(9):12140-12152. doi: 10.3390/ijms130912140. Epub 2012 Sep 24.
Rb(1)-hydrolyzing β-glucosidase from Aspergillus niger KCCM 11239 was studied to develop a bioconversion process for minor ginsenosides. The specific activity of the purified enzyme was 46.5 times greater than that of the crude enzyme. The molecular weight of the native enzyme was estimated to be approximately 123 kDa. The optimal pH of the purified enzyme was pH 4.0, and the enzyme proved highly stable over a pH range of 5.0-10.0. The optimal temperature was 70 °C, and the enzyme became unstable at temperatures above 60 °C. The enzyme was inhibited by Cu(2+), Mg(2+), Co(2+), and acetic acid (10 mM). In the specificity tests, the enzyme was found to be active against ginsenoside Rb(1), but showed very low levels of activity against Rb(2), Rc, Rd, Re, and Rg(1). The enzyme hydrolyzed the 20-C,β-(1→6)-glucoside of ginsenoside Rb(1) to generate ginsenoside Rd and Rg(3), and hydrolyzed 3-C,β-(1→2)-glucoside to generate F(2). The properties of the enzyme indicate that it could be a useful tool in biotransformation applications in the ginseng industry, as well as in the development of novel drug compounds.
对黑曲霉KCCM 11239中可水解Rb(1)的β-葡萄糖苷酶进行了研究，以开发一种用于制备稀有人参皂苷的生物转化工艺。纯化酶的比活性比粗酶高46.5倍。天然酶的分子量估计约为123 kDa。纯化酶的最适pH为4.0，该酶在pH 5.0 - 10.0范围内表现出高度稳定性。最适温度为70℃，在60℃以上酶变得不稳定。该酶受到Cu(2+)、Mg(2+)、Co(2+)和10 mM乙酸的抑制。在特异性测试中，发现该酶对人参皂苷Rb(1)有活性，但对Rb(2)、Rc、Rd、Re和Rg(1)的活性非常低。该酶水解人参皂苷Rb(1)的20-C,β-(1→6)-葡萄糖苷生成人参皂苷Rd和Rg(3)，水解3-C,β-(1→2)-葡萄糖苷生成F(2)。该酶的特性表明，它可能是人参产业生物转化应用以及新型药物化合物开发中的有用工具。
