UBC Theses and Dissertations
The binding of an afimbrial bacterial surface adhesin to glycophorin using aqueous polymer two-phase partitioning Jones, Andrew John Melvill
Colonisation by many bacteria and viruses is now thought to depend upon their ability to adhere to host cells via proteinacious surface appendages called adhesins. Information relevant to the prevention and cure of many diseases therefore is supplied by knowledge of this adhesive process, especially the chemistry of the binding and the structure of the binding molecules. At this time, the structure of very few adhesin receptors is known. Similarly, the quaternary and primary structure of only a small number of adhesins is currently available. Those associated with Escherichia coli are known in some cases to be arranged as helical coils with repeating proteinacious subunits with molecular weights of 10-30 kDa, however there is conflicting information on the distribution along these coils of the polypeptide involved in adhesion. Thermodynamic binding studies have not yet been used to clarify this problem because of the size of the receptors for the adhesins. This thesis presents a thermodynamic study of the binding between the adhesin from an F41+ E.coli and its receptor, glycophorin, from the human red blood cell membrane using an aqueous polymer two-phase system. The study shows that 2.4±0.8 glycophorin molecules bind to the predominant subunit of this adhesin, suggesting that this subunit has one binding site, since glycophorin dissolves as a dimer. It is proposed that the assay could be used, in addition, to obtain information on the chemical specificity and the thermodynamics of this particular reaction, in order to obtain a broader understanding of the colonisation and infection by this particular pathogen.
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