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Dextran and Related PolysaccharidesBy: Vicki Caligur, BioFiles 2008, 3.10, 17.

Dextran

Historically, dextrans had been long recognized as contaminants in sugar processing and other food production. Theformation of dextran in wine was shown by Pasteur to be due to the activity of microbes.1 The name dextran wascreated by Scheibler in 1874, who demonstrated dextran was a carbohydrate with the formula (C6H10O6)n and apositive optical rotation.2

Dextrans are polysaccharides with molecular weights ≥1,000 Dalton, which have a linear backbone of α-linked d-glucopyranosyl repeating units. Three classes of dextrans can be differentiated by their structural features. Thepyranose ring structure contains five carbon atoms and one oxygen atom. Class 1 dextrans contain the α(1→6)-linkedd-glucopyranosyl backbone modified with small side chains of d-glucose branches with α(1→2), α(1→3), and α(1→4)-linkage (see Figure 1). The class 1 dextrans vary in their molecular weight, spatial arrangement, type and degree ofbranching, and length of branch chains,3-5 depending on the microbial producing strains and cultivation conditions.6,7

Isomaltose and isomaltotriose are oligosaccharides with the class 1 dextran backbone structure. Class 2 dextrans(alternans) contain a backbone structure of alternating α(1→3) and α(1→6)-linked d-glucopyranosyl units with α(1→3)-linked branches. Class 3 dextrans (mutans) have a backbone structure of consecutive α(1→3)-linked d-glucopyranosylunits with α(1→6)-linked branches. One and two-dimensional NMR spectroscopy techniques have been utilized for thestructural analysis of dextrans.8

Figure 1. General structure of class 1 dextrans consisting of a linear backbone of α(1→6)-linked d-glucopyranosyl repeatingunits. The dextran may have branches of smaller chains of d-glucose linked to the backbone by α(1→2)- , α(1→3)- or α(1→4)-glycosidic bonds.

The secretion of dextrans provides an opportunity for bacteria to modulate adhesion, e.g. in tooth decay, by having a

The secretion of dextrans provides an opportunity for bacteria to modulate adhesion, e.g. in tooth decay, by having asofter or more rigid bacterial cell surface, depending on the polysaccharide itself and the pH and ionic strength. Lowbacterial adhesion occurs at low salt conditions with more rigid polysaccharides and a softer surface, while highbacterial adhesion is obtained with more flexible polysaccharides and a rigid bacterial surface. Polymer elasticity isimportant for structural integrity. and the pyranose ring is the structural unit controlling the elasticity of thepolysaccharide. This elasticity results from a force-induced elongation of the ring structure and a final transition from achair-like to a boat-like conformation of the glucopyranose ring, which plays an important role in accommodatingmechanical stress and modulating ligand binding in biological systems.9 Laboratory experiments have demonstratedthat cleavage of the pyranose rings of dextran, amylose, and pullulan convert these different polysaccharide chains intosimilar structures where all the bonds of the polymer backbone can rotate and align under force. After ring cleavage,single molecules of dextran, amylose, and pullulan display identical elastic behavior as measured by atomic forcemicroscopy.

Dextrans are found as bacterial extracellular polysaccharides. They are synthesized from sucrose by beneficial lacticacid bacteria, such as Leuconostoc mesenteroides and Lactobacillus brevis, but also by the dental plaque-formingspecies Streptococcus mutans. Bacteria employ dextran in biofilm formation10 or as protective coatings, e.g., to evadehost phagocytes in the case of pathogenic bacteria.11

The physical and chemical properties of purified dextrans vary depending on the microbial strains from which they areproduced and by the production method, but all are white and tasteless solids. Dextrans have high water solubility andthe solutions behave as Newtonian fluids. Solution viscosity depends on concentration, temperature, and molecularweight, which have a characteristic distribution.

The long history of the safety of dextrans has allowed them to be used as additives to food and chemicals, and inpharmaceutical and cosmetics manufacturing.12 Dextrans have been investigated for the targeted and sustaineddelivery of drugs, proteins, enzymes, and imaging agents.13 In medicine, clinical grades of dextrans with a molecularweight range of 75-100 kDa have been used as blood-plasma volume expanders in transfusions.14 Other applicationsinclude the use of dextrans with polyethylene glycol as components of aqueous two-phase systems for the extraction ofbiochemicals. The hydroxyl groups present in dextran offer many sites for derivatization, and these functionalizedglycoconjugates represent a largely unexplored class of biocompatible and environmentally safe compounds.

Cross-linked dextran beads are widely used for chromatography in biochemical research and industry. The classicapplication of cross-linked dextrans is as gel filtration media in packed-bed columns for the separation and purificationof biomolecules with molecular weights in the range of 0.7-200 kDa.15-17 Ion exchange chromatography utilizes dextranthat has been derivatized with positively or negatively charged moieties such as carboxymethyl (CM), diethylaminoethyl(DEAE), diethyl(2-hydroxypropyl) aminoethyl (QAE), and sulfopropyl (SP).

Sigma® offers a large variety of dextrans with high polydispersity and dextran molecular weight standards with lowpolydispersity (Mw/Mn values close to 1.0).

Other Polysaccharides

Pullulans are structural polysaccharides primarily produced from starch by the fungus Aureobasidium pullulans.18,19

Pullulans are composed of repeating α(1→6)-linked maltotriose (D-glucopyranosyl-α(1→4)-D-glucopyranosyl-α(1→4)-D-glucose) units with the inclusion of occasional maltotetraose units.20 Diffusion-ordered NMR spectroscopy has beenused to achieve a simple estimation of the molecular weight of pullulan.21 The solution properties of pullulan in waterhave been studied, and it was confirmed that pullulan molecules behave as random coils in aqueous solution.22

Dextrins are composed of D-glucopyranosyl units but have shorter chain lengths than dextrans. They start with a singleα(1→6) bond, but continue linearly with α(1→4)-linked D-glucopyranosyl units. Dextrins are usually mixtures derivedfrom the hydrolysis of starch and have found widespread use in the food, paper, textile, and pharmaceutical industries.

Dextran sulfates are derived from dextran via sulfation. They have become indispensable components in manymolecular biology techniques, including the transfer of large DNA fragments from agarose gels and rapidhybridization,23 precipitation procedures for the quantitation of high-density lipoprotein cholesterol,24 and inhibition ofvirion binding to CD4+ cells.25

Materials

Product # Image Description Molecular Formula Add to Cart

86524 CM-Dextran sodium saltBioXtra

pricing

D9885 DEAE-Dextran hydrochloridepowder

pricing

30461 DEAE-Dextran hydrochlorideBioReagent, for molecularbiology

pricing

00268 Dextran analytical standard, forGPC, 1,000

pricing

00269 Dextran analytical standard, forGPC, 5,000

pricing

00270 Dextran analytical standard, forGPC, 12,000

pricing

00271 Dextran analytical standard, forGPC, 25,000

pricing

00891 Dextran analytical standard, forGPC, 50,000

pricing

00892 Dextran analytical standard, forGPC, 80,000

pricing

00893 Dextran analytical standard, forGPC, 150,000

pricing

00894 Dextran analytical standard, forGPC, 270,000

pricing

00895 Dextran analytical standard, forGPC, 410,000

pricing

00896 Dextran analytical standard, forGPC, 670,000

pricing

31394 Dextran enzymatic synth. pricing

31430 Dextran analytical standard, forGPC, Set Mp 1,000-400,000

pricing

31416 Dextran from Leuconostocmesenteroides analyticalstandard, for GPC, Mw 1,000

pricing

31417 Dextran from Leuconostocmesenteroides analyticalstandard, for GPC, Mw 5,000

pricing

D9260 Dextran from Leuconostocmesenteroides average mol wt9,000-11,000

pricing

31418 Dextran from Leuconostocmesenteroides analyticalstandard, for GPC, Mw 12,000

pricing

31419 Dextran from Leuconostocmesenteroides analyticalstandard, for GPC, Mw 25,000

pricing

D1662 Dextran from Leuconostocmesenteroides average mol wt35,000-45,000

pricing

31420 Dextran from Leuconostoc

mesenteroides analytical

pricing

mesenteroides analyticalstandard, for GPC, Mw 50,000

D3759 Dextran from Leuconostocmesenteroides average mol wt48,000-90,000

pricing

31421 Dextran from Leuconostocmesenteroides analyticalstandard, for GPC, Mw 80,000

pricing

D4876 Dextran from Leuconostocmesenteroides average mol wt150,000

pricing

31422 Dextran from Leuconostocmesenteroides analyticalstandard, for GPC, Mw150,000

pricing

31423 Dextran from Leuconostocmesenteroides analyticalstandard, for GPC, Mw270,000

pricing

31424 Dextran from Leuconostocmesenteroides analyticalstandard, for GPC, Mw410,000

pricing

31425 Dextran from Leuconostocmesenteroides analyticalstandard, for GPC, Mw670,000

pricing

49297 Dextran from Leuconostocmesenteroides analyticalstandard, for GPC, Mw1,400,000

pricing

D5376 Dextran from Leuconostocmesenteroides average mol wt1,500,000-2,800,000

pricing

D5501 Dextran from Leuconostocmesenteroides industrialgrade, average mol wt5,000,000-40,000,000

pricing

31397 Dextran from Leuconostocmesenteroides Mr ~60,000

pricing

31398 Dextran from Leuconostocmesenteroides Mr ~200,000

pricing

31388 Dextran from Leuconostoc spp.Mr ~6,000

pricing

31389 Dextran from Leuconostoc spp.Mr ~40,000

pricing

31390 Dextran from Leuconostoc spp.Mr ~70,000

pricing

09184 Dextran from Leuconostoc spp.Mr ~100,000

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95771 Dextran from Leuconostoc spp.Mr ~2,000,000

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31392 Dextran from Leuconostoc spp.Mr ~500,000

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31387 Dextran from Leuconostoc spp.Mr 15,000-25,000

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01468 Dextran cross-linked G-25 50-150 µm particle size

pricing

40359 Dextran cross-linked G-50 50-150 µm

pricing

94504 Dextran cross-linked G-50 20-80 µm

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68263 Dextran cross-linked G-50 100-300 µm particle size

pricing

D4911 Dextran sulfate sodium saltfrom Leuconostoc spp. mol wt6,500-10,000

pricing

D6924 Dextran sulfate sodium saltfrom Leuconostoc spp.average mol wt 9,000-20,000

pricing

D6001 Dextran sulfate sodium saltfrom Leuconostoc spp.average mol wt >500,000(dextran starting material),contains 0.5-2.0% phosphatebuffer, pH 6-8

pricing

D8906 Dextran sulfate sodium saltfrom Leuconostoc spp. formolecular biology, average Mw

>500,000 (dextran startingmaterial), contains 0.5-2%phosphate buffer

pricing

31404 Dextran sulfate sodium saltfrom Leuconostoc spp. Mr

5,000

pricing

D2006 Dextrin from corn Type I,powder

pricing

D2131 Dextrin from corn commercialgrade, Type II, powder

pricing

31410 Dextrin from maize starch 10 pricing

31414 Dextrin from maize starch 20 pricing

D4894 Dextrin from potato starch TypeIV, powder

pricing

31400 Dextrin from potato starch formicrobiology

pricing

P4516 Pullulan from Aureobasidiumpullulans suitable for substratefor pullulanase

pricing

96351 Pullulan Standard Set set ofanalytical standards, for GPC,Mp 342-710′000

pricing

References

1. Pasteur, L., Bull. Soc. Chim. Paris, 30-31 (1861).2. Scheibler, C., Z. Ver. Dtsch. Zucker-Ind., 24, 309-335 (1874).3. Robyt, J.F., in: Encyclopedia of Polymer Sci. Eng., J.I.Kroschwitz (ed.), 4, 752-767 (1986), Wiley-VCH.4. Cheetham, N.W.H., et al., Dextran structural details from high-field proton NMR spectroscopy. Carbohydr. Polym.14, 149-158 (1990).

5. Naessens, M., et al., Leuconostoc dextransucrase and dextran: production, properties and applications. J. Chem.Technol. Biotechnol., 80, 845-860 (2005).

6. Kim, D., et al., Dextran molecular size and degree of branching as a function of sucrose concentration, pH, andtemperature of reaction of Leuconostoc mesenteroides B-512FMCM dextransucrase. Carbohydr. Res., 338, 1183-11889 (2003).

7. Côté, G.L., and Leathers, T.D., A method for surveying and classifying Leuconostoc spp. glucansucrasesaccording to strain-dependent acceptor product patterns. J. Ind. Microbiol. Biotechnol. 32, 53-60 (2005).

8. Maina, N.H., et al., NMR spectroscopic analysis of exopolysaccharides produced by Leuconostoc citreum andWeissella confusa. Carbohydr. Res., 343, 1446-1455 (2008).

9. Marszalek, P.E., et al., Polysaccharide elasticity governed by chair-boat transitions of the glucopyranose ring.Nature, 396, 661-664 (1998).

10. Banas, J.A., and Vickermann, M.M., Glucan-binding proteins of the oral streptococci. Crit. Rev. Oral Biol. Med., 14,89-99 (2003).

11. Meddens, M.J., et al., Br. J. Exp. Pathol., 65, 257-265 (1984).12. Kato, I., Fragrance J., 33, 59-64 (2005).13. Mehvar, R., Dextrans for targeted and sustained delivery of therapeutic and imaging agents. J. Controlled

Release, 69, 1-25 (2000).14. Terg, R., et al., Pharmacokinetics of Dextran-70 in patients with cirrhosis and ascites undergoing therapeutic

paracentesis. J. Hepatol., 25, 329-333 (1996).15. Porsch, B., and Sundelöf, L.-O., Size-exclusion chromatography and dynamic light scattering of dextrans in water:

Explanation of ion-exclusion behaviour. J. Chromatogr. A, 669, 21-30 (1994).16. Neyestani, T.R., et al., Isolation of α-lactalbumin, β-lactoglobulin, and bovine serum albumin from cow’s milk using

gel filtration and anion-exchange chromatography including evaluation of their antigenicity. Protein Expres. Purif.,29, 202-208 (2003).

17. Penzol, G., et al., Use of dextrans as long and hydrophilic spacer arms to improve the performance of immobilizedproteins acting on macromolecules. Biotechnol. Bioeng., 60, 518-523 (1998).

18. Gibson, L.H., and Coughlin, R.W., Optimization of high molecular weight pullulan production by Aureobasidium

18. Gibson, L.H., and Coughlin, R.W., Optimization of high molecular weight pullulan production by Aureobasidiumpullulans in batch fermentations. Biotechnol. Prog., 18, 675-678 (2002).

19. Leathers, T.D., Biotechnological production and applications of pullulan. Appl. Microbiol. Biotechnol., 62, 468-473(2003).

20. Catley, B.J., Pullulan, a relationship between molecular weight and fine structure. FEBS Lett., 10, 190-193 (1970).21. Viel, S., et al., Diffusion-ordered NMR spectroscopy: a versatile tool for the molecular weight determination of

uncharged polysaccharides. Biomacromolecules, 4, 1843- 1847 (2003).22. Nishinari, K., et al., Solution properties of pullulan. Macromolecules, 24, 5590-5593 (1991).23. Wahl, G.M., et al., Efficient transfer of large DNA fragments from agarose gels to diazobenzyloxymethyl-paper and

rapid hybridization by using dextran sulfate. Proc. Natl. Acad. Sci. USA, 76, 3683-3687 (1979).24. Warnick, G.R., et al., Dextran sulfate-Mg2+ precipitation procedure for quantitation of high-density-lipoprotein

cholesterol. Clin. Chem., 28, 1379-1388 (1982).25. Mitsuya H., et al., Dextran sulfate suppression of viruses in the HIV family: inhibition of virion binding to CD4+

cells. Science, 240, 646-649 (1988).