Studies on dextran and dextran derivatives. I. Properties of native dextran in different solvents

Abstract

SynopsisLight-scattering, sedimentation, viscosity, and reducing power measurements have been carried out on a sample of native dextran from Leuemstoc mesenteroides B-512. The results are discueaed in relation to the structure, polydispersity, and branching of the polysaccharide. The effect of different solvents on the behavior of native dextran has been studied. The molecular weight of the dextran remaim unchanged in 'all the solvents used, while the radius of gyration shows a significant increase in some of them (concentrated salts, urea, and glucose solutions); in water-methanol solutions the radius of gyration slightly decreases.Chemical and physicochemical studies reported in the literature' provide a satisfactory picture of the structure of the polysaccharide dextran and of its behavior in solution. However, the exact shape, size, molecular weight distribution, and branching of different samples of native dextran may be uncertain, owing to variabilities in the properties of the polymer even if it is obtained from the same strain of microorganism.2*3 In the course of investigations on the properties of dextran derivatives, it has been therefore necessary to characterize by different physicochemical methods the sample of native dextran used. Moreover, it seemed interesting to study the effect of different solvents on some properties of native dextran. It was hoped that such studies might give additional information on the behavior of the polymer in solution. Also, experiments of this kind are a necessary prerequisite for the interpretation of the effects of the same solvents on the properties of modified dextrans and on the interactions of native and modified dextrans. MATERIAL AND METHODSAll the experiments were carried out on a sample of native dextran synthesized by dextransucrase of Leuconostoc mesenteroides, NRRL B-512(F), P.P. 40-B (supplied by the Northern Regional Research Laboratory of the U.S. Department of Agriculture, Peoria, Ill.).

Interaction of nonionic dextrans with silver bromide hydrosols

“…However, because of the smaller size of dextran molecules in the methanol-water solvent (Table 2; also Refs. 28,29,30), the coagulation maximum appears at higher polymer concentration. In the presence of dextrans of lower molecular weights or in less concentrated sols somewhat more electrolyte is needed for sol destabilization than what remains in solution as a result of silver halide precipitation from AgNOa and KBr.…”

Quantitative characterization of the concentration‐dependent interaction between molecules of Dextran 70 in aqueous solution: Measurement and analysis in the context of thermodynamic and compressible sphere models

“…Solutions were prepared in phosphate‐buffered saline (0.005 M sodium phosphate and 0.15 M NaCl at pH 7.4) and equilibrated by extensive dialysis using Pierce 10000 MWCO Slide‐A‐Lyzer Dialysis cassettes (Thermo Scientific). Concentrations were determined by differential refractometry at 589 nm, using an Arias 500 Abbe refractometer (Reichert Instruments, Buffalo, NY), and a refractive increment of 0.150 cm 3 /g …”

Shear-induced structure in enzymatically-synthesized dextran solutions

“…In order to determine to what extent hydrogen bonding is playing a role in the intermolecular interactions occurring during structure formation, we added urea to the dextran solution. The presence of urea in aqueous solutions is known to break many of the hydrogen bonds [27,28]. Figure 10 shows the inftuence of the addition of urea on the structure formation.…”