Sodium periodate dextran

Quench the reaction by immediate gel filtration on a desalting column. If a dextran-based resin is used for the chromatography, the support itself will react with sodium periodate to quench excess reagent. Alternatively, N-acetylmethionine may be added to quench the reaction, because the thioether of the methionine side chain will react with periodate to form sulfoxide or sulfone products (Geoghegan and Stroh, 1992). In addition, sodium... 

Figure 25.12 Dextran polymers can be oxidized with sodium periodate to create a polyaldehyde derivative. Note that additional oxidation may occur to cleave off another carbon atom and create an aldehyde on the adjacent C—OH group.

Protocol for Oxidizing Dextran with Sodium Periodate... 

Dissolve dextran (Polysciences) of molecular weight between 10,000 and 40,000 in the sodium periodate solution with stirring. 

Quench the reaction by the addition of 0.1 ml of glycerol per milliliter of reaction solution. Alternatively, the reaction may be stopped by immediate gel filtration on a Sephadex G-25 column. The dextran beads of the chromatography support will react with sodium periodate to quench excess reagent. To quench the reaction with cellular samples, wash the cells with buffer to remove remaining traces of periodate. 

The dextran polymer contains adjacent hydroxyl groups on each glucose monomer. These diols may be oxidized with sodium periodate to cleave the associated... 

Weissleder et al. [84] first showed that the human transferrin receptor (hTfR) can be used to internalize MRI contrast agents. The hTfR regulates cellular uptake of iron from transferrin, a plasmatic iron transport protein [85], via a receptor mediated endocytosis mechanism. Thus, MION particles (dextran coated iron oxide) were oxidized with sodium periodate. Holotransferrin was added and the resulting Schiff base adduct was reduced with sodium cyanoborohydride to give transferrin labeled MIONs, Tf-MION (Scheme 3). 

Periodate oxidation. Aldehyde groups can be easily introduced in most polysaccharides by reaction with sodium periodate. Vicinal diol structures give rise to dialdehydes. For dextran (I) having three adjacent hydroxyl groups in each non-branched anhydro glucopyranoside repeat unit the oxidation is a two step reaction ... 

Coatings of allyldextran monolayers were carried out on PS chips activated with y -irradiation. In a second step, sodium periodate chemistry was applied to functionalize the dextran layer, followed by the coupling with Streptavidin and/or Neutravidin. The modified PS surfaces are highly hydrophilic with low... 

Periodate Oxidation mainly of polysaccharide supports has become a popular activation technique for protein immobilization [149]. Sodium periodate (Nal04) can react with vicinal cw-hydroxyl groups on cellulose, dextran, or any other diols to produce aldehyde groups. These aldehyde groups can easily be transformed into secondary amines by reductive oxidation or to hydrazides by reaction with dihydrazine. Further attachment of ligands or spacer molecules can be performed via primary amino groups. 

Dextran was oxidized with sodium periodate to the corresponding polyaldehyde and daunomycin was coupled with a part of the aldehydes via its amino sugar. This complex was further bound to the lysines of the antibody. This conjugate can either be used directly or stabilized by further reduction with sodium borohydride. 

Kinetic evidence for hemiacetal formation during the oxidation of dextran by aqueous sodium periodate has been interpreted in terms of intra-residual hemiacetal formation by singly oxidized residues, and inter-residual hemiacetal formation between doubly oxidized residues and intact adjacent d-glucose residues. ... 

A dextran solution was reacted with an excess of sodium periodate and the final periodate consumption as well as the amount of formic acid formed were determined. 

Table 2. Partial oxidation of dextran with sodium periodate.

Aldehyde-containing macromolecules will react spontaneously with hydrazide compounds to form hydrazone linkages. The hydrazone bond is a form of Schiff base that is more stable than the Schiff base formed from the interaction of an aldehyde and an amine. The hydrazone, however, may be reduced and further stabilized by the same reductants utilized for reductive amination purposes (Chapter 3, Section 4.8). The addition of sodium cyanoborohydride to a hydrazide-aldehyde reaction drives the equilibrium toward formation of a stable covalent complex. Mallia (1992) found that adipic acid dihydrazide derivatization of periodate-oxidized dextran (containing multiple formyl functionalities) proceeds with much greater yield when sodium cyanoborohydride is present. 

With 0.5M sodium hydroxide as eluent, Sephadex G-50 effects fractionation in the molar mass range 1000-15000 dalton and can be used for a period of 3-4 weeks with a single calibration carried out with proteins and polypeptides of known molar mass, as revealed by Figure 10. Relative retention volumes 0.0 and 1.0 are defined with Blue Dextran and phenol, respectively. 

Preliminary examinations of dextran structures were conducted by optical rotation, infrared spectroscopy and periodate-oxidation reactions. More detailed results can be achieved by methylation analysis [19]. The hydroxyl groups are methylated with methyl iodide after activation with sodium methylsulfinyl carbanion (Fig. 2). The methyl dextran is hydrolysed to the corresponding different methylated monosaccharides, which are furthermore reduced and peracetylated. The resulting alditol acetates of methylated sugars are separated by gas chromatography and identified by their retention times. In particular, a combined capillary gas-liquid chromatography/mass... 

Reduced dextran dialdehydes. The reaction of dextran (D-OH) with sodium metaperiodate is a two step reaction leading to different kinds of aldehyde functions. Although the aldehyde content can not be precisely predicted from the amount of periodate added, by approximation 1.5 equivalents of periodate are required per dialdehyde structure. By varying the amount of periodate added to the polysaccharide dextran dialdehydes with variable degree of oxidation were obtained. In order to avoid interaction of the polyaldehyde (D-CH=0) with the dextranases the aldehyde groups were subsequently reduced by reaction with sodium borohydride ... 

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