Dextran is a D-glucosyl homopolysaccharide which has a-1,6 glucosidic linkages with different branches through α-1,2, α-1,3, and α-1,4 linkages correspondingly classified as group A, B and C. It can be synthesized from sucrose by cell-free filtrate.
Dextrans are polysaccharides with molecular weights ≥1,000 Dalton, with a linear backbone of α-linked D-glucopyranosyl repeating units. Dextrans are found as bacterial extracellular polysaccharides. They are synthesized from sucrose by Leuconostoc mesenteroides and Lactobacillus brevis. Bacteria employ dextran in biofilm formation or as a protective coating to evade host phagocytes in the case of pathogenic bacteria.
Dextran from Leuconostoc mesenteroides (Mw: 25,000) may be used as an analytical standard to calibrate the column for gel permeation chromatography (GPC).
Markers-dextran with 25000 Da has been used as standard in gel chromatography analysis to determine fractional composition of protein, carbohydrate, phenolic surface active substances in base wine.
Use of dextrans as long and hydrophilic spacer arms improves the performance of immobilized proteins acting on macromolecules.