Characterization of a sucrose phosphorylase from Leuconostoc mesenterides for the synthesis of α-arbutin

Abstract:

Sucrose phosphorylase (SPase) gene from Leuconostoc mesenteroides ATCC 12291 was synthesised after codon optimization, and inserted into pET-28a plasmid to generate pET-28a-spase. The recombinant strain Escherichia coli BL21 (DE3)/pET-28a-spase was induced for Spase expression. The recombinant protein Spase was purified and characterized. The specific enzyme activity of SPase was 213.98 U/mg, the purification ratio was 1.47-fold, and the enzyme activity recovery rate was 87.80%. The optimal temperature and the optimal pH of the SPase were identified to be 45 °C and 6.5 respectively, and Km, Vmax and kcat of the SPase for sucrose was 128.8 mmol/L, 2.167 μmol/(mL·min), and 39 237.86 min–1. The recombinant SPase was used for α-arbutin production from hydroquinone and the reaction process was evaluated. The optimal conditions for synthesis of α-arbutin by SPase were 40 g/L hydroquinone, 5:1 molar ratio of sucrose and hydroquinone, and 250 U/mL recombinant SPase at pH 7.0 and 30 °C for 24 h in the dark, and then 500 U/mL glucoamylase was added at 40°C for 2.5 h. Under the optimized process, the yield of α-arbutin reached 98 g/L, and the hydroquinone conversion rate was close to 99%. In summary, the recombinant SPase was cloned and characterized, and its application for α-arbutin production was feasible.