Polyaldehyde Activation and Coupling

Proteins may be modified with oxidized dextran polymers under mild conditions using sodium cyanoborohydride as the reducing agent. The reaction proceeds primarily through e-amino groups of lysine located at the surface of the protein molecules. The optimal pH for the reductive amination reaction is an alkaline environment between pH 7 and 10. The rate of reaction is greatest at pH 8-9 (Kobayashi and Ichishima, 1991), reflecting the efficiency of Schiff base formation at this pH. 

The following protocol for creating the polyaldehyde dextran derivative is based on the method of Bernstein et al. (1978). 

Protocol for Oxidizing Dextran with Sodium Periodate 

Dissolve sodium periodate (NalC ) (Sigma) in 500 ml of deionized water at a concentration of 0.03 M (6.42 g). Protect from light. 

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

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

Carton-Carbon Bond Cleavage with Oxidation to Aidehyde Residues 

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