首页|A novel fusion levansucrase improves thermostability of polymerization and production of high molecular weight levan
A novel fusion levansucrase improves thermostability of polymerization and production of high molecular weight levan
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NSTL
Elsevier
A novel fusion levansucrase (TPS-SacB-T305A) was constructed by adding to SacB-T305A an extra C-terminus of the trehalose-6-phosphate synthase (TPS) involved in its thermostability. The fusion TPS-SacB-T305A was expressed in Escherichia coli and purified, its hydrolytic V-max and K-m were about 39.53 mu mol/(minute*mg protein) and 13.36 mmol/L, respectively. The levan production reached 71.6 +/- 2.06 g/L with a conversion yield of 35.8 +/- 1.03% using sucrose as substrates under the present optimum condition of polymerization and the products were characterized by NMR and FT-IR. Interestingly, the optimum temperature of fused TPS-SacBT305A was 15 degrees C higher than that of free SacB-T305A on levan polymerization, and the half-life at 40 degrees C of fusion enzyme increased to more than 4-fold. The proportion of high molecular weight (HMW) levan (approximately 2000 kDa) to total polysaccharides was raised tremendously from approximately 4% (catalyzed by free SacB-T305A) to approximately 91% (catalyzed by TPS-SacB-T305A). The present study provides a potential industrial enzyme to produce HMW levan and helps to explore the mechanism of levan polymerization.
NSTL
Elsevier
