Insulin self-association prevention

Some proteins self-associate in aqueous solution to form oligomers. Insulin, for example, exists in several associated states the zinc hexamer of insulin is a complex of insulin and zinc which dissolves slowly into dimers and eventually monomers following its subcutaneous administration, so giving it long-acting properties. In most cases, however, it is desirable to prevent association such that only monomeric or dimeric forms are present in the formulations and a more rapid absorption is achieved. Recent studies have been directed towards engineering insulin molecules which are not prone to association, " or the prevention of association through the addition of surfactants. Protein self-association is a reversible process, i.e. alteration of the solvent properties can lead to the re-formation of the monomeric native protein. There is an important distinction between this association... 

Touitou, E., Alhaique, F., Fisher, P., Memoli, A., Riccieri, F. M., and Santucci, E., 1987, Prevention of molecular self-association by sodium salicylate Effect on insulin and 6-carboxfluorescein, J. Pharm. Sci. 76 791-793. 

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