Identification and Characterization of a Thermostable GH36 α-Galactosidase from <i>Anoxybacillus</i> <i>vitaminiphilus</i> WMF1 and Its Application in Synthesizing Isofloridoside by Reverse Hydrolysis
An α-galactosidase-producing strain named <i>Anoxybacillus vitaminiphilus</i> WMF1, which catalyzed the reverse hydrolysis of <span style="font-variant: small-caps;">d</span>-galactose and glycerol to produce isofloridoside, was isolated from soil. The α-galactosida...
| Main Authors: | , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2021-10-01
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| Series: | International Journal of Molecular Sciences |
| Subjects: | |
| Online Access: | https://www.mdpi.com/1422-0067/22/19/10778 |
| Summary: | An α-galactosidase-producing strain named <i>Anoxybacillus vitaminiphilus</i> WMF1, which catalyzed the reverse hydrolysis of <span style="font-variant: small-caps;">d</span>-galactose and glycerol to produce isofloridoside, was isolated from soil. The α-galactosidase (galV) gene was cloned and expressed in <i>Escherichia coli</i>. The galV was classified into the GH36 family with a molecular mass of 80 kDa. The optimum pH and temperature of galV was pH 7.5 and 60 °C, respectively, and it was highly stable at alkaline pH (6.0–9.0) and temperature below 65 °C. The specificity for p-nitrophenyl α-<span style="font-variant: small-caps;">d</span>-galactopyranoside was 70 U/mg, much higher than that for raffinose and stachyose. Among the metals and reagents tested, galV showed tolerance in the presence of various organic solvents. The kinetic parameters of the enzyme towards p-nitrophenyl α-<span style="font-variant: small-caps;">d</span>-galactopyranoside were obtained as <i>K</i><sub>m</sub> (0.12 mM), <i>V</i><sub>max</sub> (1.10 × 10<sup>−3</sup> mM s<sup>−1</sup>), and <i>K</i><sub>cat</sub><i>/K</i><sub>m</sub> (763.92 mM<sup>−1</sup> s<sup>−1</sup>). During the reaction of reverse hydrolysis, the enzyme exhibited high specificity towards the glycosyl donor galactose and acceptors glycerol, ethanol and ethylene glycol. Finally, the isofloridoside was synthesized using galactose as the donor and glycerol as the acceptor with a 26.6% conversion rate of galactose. This study indicated that galV might provide a potential enzyme source in producing isofloridoside because of its high thermal stability and activity. |
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| ISSN: | 1661-6596 1422-0067 |