Effective enzymatic synthesis of lactosucrose and its analogues by beta-D-galactosidase from Bacillus circulans.
Effective enzymatic synthesis of lactosucrose and its analogues by beta-D-galactosidase from Bacillus circulans.
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DOI：
10.1021/jf9002494
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发表时间：
2009-03
影响因子：
6.1
通讯作者：
Wei Li;Xiaoli Xiang;S. Tang;Bing Hu;Lin Tian;Yi Sun;Hong Ye;Xiaoxiong Zeng
中科院分区：
文献类型：
--
作者：
Wei Li;Xiaoli Xiang;S. Tang;Bing Hu;Lin Tian;Yi Sun;Hong Ye;Xiaoxiong Zeng
在本研究中，环状芽孢杆菌的β-D-半乳糖苷酶被证明是从乳糖和蔗糖中生产乳糖((beta-d-Galp-(1-->；4)-alpha-d-Glcp-(1-->；2)-beta-d-Fruf，I)及其类似物的合适生物催化剂。在乳糖的水解过程中，四种转移产物的形成被高效液相色谱折射率检测器跟踪。此外，从反应混合物中分离出转移产物，鉴定为I，beta-d-Galp-(1-->；3)-alpha-d-Glcp-(1-->；2)-beta-d-Fruf(II)，beta-d-Galp-(1-->；4)-beta-d-Galp-(1-->；4)-alpha，β-d-Glcp(III)和β-d-Galp-(1->；4)-β-d-Galp-(1-->；4)-α-d-Glcp-(1->；2)-β-d-Fruf(IV)的电喷雾电离源质谱和核磁共振波谱。在反应的初始阶段，转移产物的生成顺序为III>；I>；IV>；II，转移产物的水解率也存在相同的关系。考察了反应温度、反应时间、底物浓度、给体/受体摩尔比、酶浓度等合成条件对转移产物形成的影响。结果表明，合成I和II的最佳合成条件不同，在最佳合成条件下，总转移产物的量在最初的4h内不断增加，在反应4h时总转移产物的产量达到最大值146g/L。
In the present study, beta-d-galactosidase from Bacillus circulans was proved to be a suitable biocatalyst for the production of lactosucrose (beta-d-Galp-(1-->4)-alpha-d-Glcp-(1-->2)-beta-d-Fruf, I) and its analogues from lactose and sucrose. During the hydrolysis of lactose, the formation of four transfer products was followed by high performance liquid chromatography with refraction index detector. In addition, the transfer products were isolated from the reaction mixture and identified to be I, beta-d-Galp-(1-->3)-alpha-d-Glcp-(1-->2)-beta-d-Fruf (II), beta-d-Galp-(1-->4)-beta-d-Galp-(1-->4)-alpha,beta-d-Glcp (III), and beta-d-Galp-(1-->4)-beta-d-Galp-(1-->4)-alpha-d-Glcp-(1-->2)-beta-d-Fruf (IV) by mass spectrometry with an electrospray ionization source and nuclear magnetic resonance spectroscopy. The order for the production of the transfer products was III > I > IV > II in the initial stage of the reaction, and the same relationship was also observed for the hydrolytic rates of transfer products. Furthermore, the effects of synthetic conditions including reaction temperature, reaction time, concentration of substrate, molar ratio of donor/acceptor, and enzyme concentration on the formation of transfer products were examined. We found that the optimal synthetic conditions were different for the production of I and II. Under the optimal conditions, the amount of total transfer products kept increasing during the early 4 h incubation, and a maximum yield of 146 g/L for total transfer products was obtained at 4 h of reaction.