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- Title
Synthesis of oligosaccharides with lactose and N-acetylglucosamine as substrates by using β- d-galactosidase from Bacillus circulans.
- Authors
Wei Li; Yi Sun; Hong Ye; Xiaoxiong Zeng
- Abstract
In the present study, β- d-galactosidase from Bacillus circulans was proved to be a suitable biocatalyst for the production of N-acetyl-oligosaccharides with lactose and N-acetylglucosamine (GlcNAc) as biocatalyst. During the hydrolysis of lactose, apart from no ultraviolet absorption oligosaccharides such as β- d-Gal p-(1 → 6)- d-Glc p (6′-allolactose) and β- d-Gal p-(1 → 4)-β- d-Gal p-(1 → 4)- d-Glc p (4′-galactosyl-lactose), the formation of four N-acetyl-oligosaccharides was followed by high-performance liquid chromatography with a diode-array detector. The four N-acetyl-oligosaccharides were isolated from the reaction mixture and identified to be as β- d-Gal p-(1 → 4)- d-Glc pNAc (LacNAc, I), β- d-Gal p-(1 → 6)- d-Glc pNAc (allo-LacNAc, II), β- d-Gal p-(1 → 4)-β- d-Gal p-(1 → 4)- d-Glc pNAc ( III), β- d-Gal p-(1 → 4)-β- d-Gal p-(1 → 4)-β- d-Gal p-(1 → 4)- d-Glc pNAc ( IV) by authentic standards and the spike technique or high-resolution mass spectrometry with an electrospray ionization source and nuclear magnetic resonance spectroscopy. Furthermore, the effects of synthetic conditions including reaction temperature, concentration of substrate, molar ratio of donor/acceptor and enzyme concentration on the formation of N-acetyl-oligosaccharides were examined. We found that the optimal synthetic conditions were different for production of oligosaccharides with β-(1 → 4) linkages and β-(1 → 6) linkage. The optimal reaction conditions for I, III and IV were 40 °C, 0.50 M lactose and 0.50 M GlcNAc and 1.0 U/mL of enzyme. Under such conditions, the N-acetyl-oligosaccharides formed were composed of 28.75% of I, 2.29% of II, 9.47% of III and 5.67% of IV. On the other hand, suitable reaction conditions found for II were 40 °C, 0.50 M lactose and 0.50 M GlcNAc and 2.0 U/mL of enzyme.
- Subjects
OLIGOSACCHARIDES; LACTOSE; ENZYMES; HYDROLYSIS; LIQUID chromatography; ELECTROSPRAY ionization mass spectrometry; NUCLEAR magnetic resonance spectroscopy
- Publication
European Food Research & Technology, 2010, Vol 231, Issue 1, p55
- ISSN
1438-2377
- Publication type
Article
- DOI
10.1007/s00217-010-1254-2