Dextran is a glucose polymer linked by α-1,6 bonds.Different molecular weight dextrans have different applications.Dextran T2000 is a dextran with a heavy average molecular weight of around 2 MDa.It can be used as a food additive.T2000 is a high-end polysaccharide product.It can be used in medical testing to separate various types of proteins in blood.Currently, there are few reports on the enzymatic directed synthesis of dextran T2000.In this paper, the dextransucrase derived from Leuconostoc mesenteroides 0326 and the dextranase BMdex derived from Brevibacterium fuscum were linked by a linker.This study designed and constructed the specific fusion enzyme, achieving a one-step method for the direct preparation of dextran T2000.A fusion enzyme with dual enzyme activity was constructed and successfully expressed in Escherichia coli.The optimal pH and temperature for dextransucrase in the fusion enzyme were 5.5 and 30 ℃.The optimal pH and temperature for dextranase in the fusion enzyme were 9.0 and 50 ℃.0.1 g/mL sucrose solution was used as substrate and fusion enzyme with a final enzyme activity of 5 U/mL was added.The reaction was carried out at 25 ℃ for 24 hours at 120-180 r/min.The reaction solution was successfully isolated and purified to obtain dextran with a heavy average molecular mass of about 2 MDa.And the reaction yield could reach 32.6%.The results of the study provided a new pathway for the enzyme-directed preparation of high-molecular polysaccharides.
CAI Baohong
,
ZHANG Xinyu
,
XIA Bingbing
,
WU Yuanyuan
,
YANG Jingwen
,
ZHANG Hongbin
. Construction and enzymatic properties of a fusion enzyme for directed biosynthesis of dextran T2000[J]. Food and Fermentation Industries, 2025
, 51(5)
: 103
-110
.
DOI: 10.13995/j.cnki.11-1802/ts.038650
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