Protein Self-Association

Question In what ways can proteins self-associate to form geometrically regular oligomers ... 

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... 

It is one of the great wonders of cell physiology that is yet to be fully understood. However, much progress has been made in the past decade. Some stmctural proteins self-associate adjacent to a lipid biolayer as they build up an igloo-like structure they enclose a small spherical vesicle that moves to a new site in the cell. 

Gottschalk, M., Venn, K., and Halle, B. 2003. Protein self-association in solution The bovine pancreatic trypsin inhibitor decamer. Biophys. J. 84 3941-3958. 

This approach to the study of protein self-association offers many advantages over the other methods mentioned above. The instrumentation and operation are simple, involving only a chromatography column packed with a suitable gel filtration matrix for the protein of interest, a solvent... 

To study protein self-association over a wide concentration range, a variable wavelength UV detector is recommended. This allows for the selection of a wavelength to either minimize absorbance at high protein concentrations or to maximize absorbance at low protein concentrations. Several excellent instruments are on the market. We have used the Isco V4 variable wavelength detector successfully. 

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