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Characterization of the Cross-Linked Enzyme Aggregates of a Novel Î²-Galactosidase, a Potential Catalyst for the Synthesis of Galacto-Oligosaccharides
- Li, Liang, Li, Gang, Cao, Li-chuang, Ren, Guang-hui, Kong, Wei, Wang, Si-di, Guo, Geng-Shen, Liu, Yu-Huan
- Journal of agricultural and food chemistry 2015 v.63 no.3 pp. 894-901
- beta-galactosidase, catalysts, crosslinking, galactooligosaccharides, genomic libraries, polymerization, storage quality, syrups, thermal stability
- A novel Î²-galactosidase (Bgal1-3) was isolated from a marine metagenomic library and then its cross-linked enzyme aggregates (CLEAs) were prepared. The enzymatic properties of Bgal1-3-CLEAs were studied and compared with that of the free enzyme. The thermostability and storage stability of Bgal1-3 were significantly improved after it was immobilized as CLEAs. The galactose-tolerance of the enzyme was also enhanced after the immobilization, which could relieve the inhibitory effect and then tends to be beneficial for the galacto-oligosaccharides (GOS) synthesis. Moreover, higher GOS yield was achieved (59.4 Â± 1.5%) by Bgal1-3-CLEAs compared to the free counterpart (57.1 Â± 1.7%) in an organicâaqueous biphasic system. The GOS content and composition of the syrups synthesized by the free enzyme and Bgal1-3-CLEAs were similar and they both contained at least seven different oligosaccharides with the degree of polymerization (DP) ranging between 3 and 9. Furthermore, Bgal1-3-CLEAs maintained 82.1 Â± 2.1% activity after ten cycles of reuse; the GOS yield of the tenth batch was 52.3 Â± 0.3%, which was still higher than that of the most former reports. To the best of our knowledge, this is the first report on the GOS synthesis using CLEAs of Î²-galactosidase in an organicâaqueous biphasic system. The study not only further expands the application scope of CLEA, but also provides a potential catalyst for the synthesis of GOS with low cost.