Structural analysis and characterization of a clinically important low molecular weight natural dextran synthesized by Leuconostoc lactis KU665298 dextransucrase

Abstract

Dextransucrases are glucosyltransferases that catalyze the transfer of -D-glucopyranose residues from sucrose to low molecular weight acceptors, forming oligos and polysaccharides. The main dextransucrase reaction product is dextran, along with the release of fructose. Dextran is a linear polymer of glucose joined mainly by  (1  6) links and fewer  (1  2),  (1  3) and/or  (1  4) links. The structural characteristics or the frequency and type of linkage in dextran are dependent on the natu re of the enzyme a nd type of producing microorganism. It has acknowledgeable industrial applications in medical, pharmaceutical, food, textile and chemical industries, depending on its structural characteristics. This paper offers the physical and chemical characterization of a clinically important dextran produced by dextransucrase of a newly isolated strain of L. lactis KU665298 in a laboratory fermenter. Structural analysis of dextran by FTIR, 1 H NMR, 13 C NMR confirmed the presence of a large percentage of -(1  6) linear linkages with very few -(1  3) branch points. The surface morphology and molecular weight distribution of purified dextran has also been included in this study.