Amines with NHS-Aldehydes SFB and SFPA

Amide Bond Formation with Terminal Aldehyde 

Dissolve a macromolecule containing amine groups at a concentration of 1-10 mg/ml in a buffer having a pH of 7—9 (i.e., 0.1 M sodium phosphate, pH 7.5). Avoid amine-containing or nucleophilic buffers such as Tris, glycine, or imidazole (see Chapter 2, Section 1.4). 

Dissolve SFB or SFPA (Molecular Probes) in DMF. The concentration should be such that a small aliquot can be added to the reaaion medium to obtain about a 10-fold excess of modifying reagent over the amount of amines to be modified. Add no more than 100 p.1 of the modifier/DMF solution to each milliliter of the macromolecule solution prepared in (1). 

Purify the modified macromolecule from excess reagent and reaction byproducts by dialysis or gel filtration. 

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