Expression and characterization of dextransucrase from leuconostoc citreum ABK-1

Abstract

Dextransucrase is an enzyme in the glycoside hydrolase 70 family that catalyze the hydrolysis of sucrose to fructose and glucose, the glucose residues are transferred to synthesize dextran via transglycosylation reaction. Dextransucrase from Leuconostoc citreum ABK-1 (Lcdextransucrase ), which has 99.5% homology with dextransucrase in the NCBI database, was cloned, expressed, and purified. The size of the Lcdextransucrase was predicted by ExPASy and the result showed that its size was 168 kDa with a pI of 5.15. Protein expression was confirmed by western blot analysis. Lcdextransucrase was purified through Ni-sepharose coupled with DEAE anion exchange column chromatography to approximately 80% purity. Moreover, the dextran product was analyzed by TLC, HPAEC-PAD, and NMR confirming that the product was dextran where glucose residues were mainly linked via a alpha-1,6 with some alpha-1,2 or alpha-1,3 branching. The dextran product may be applied and use as a prebiotic or functional food.