Jeremy Flowers - University of Waterloo

Placement: Concordia University
Supervisor: Dr. Ann English

The Nature of the Interaction Between Denaturants and Polypeptides

The interactions between denaturants and proteins is under investigation using the FTIR spectrum in the amide 1 region. Arg, Asp, Asn and Lys homo-polypeptides are being used to establish how different amino acid side chains interact with denaturants. Guanidine-HCl (Gdn-HCl) has been used to show that association between the denaturant and various polypeptides does occur. Gdn-HCl has a positive charge, hence it was deduced that a possible Cl- bridge develops between the denaturant and Lys side chain. SCN is expected form a stronger salt bridge, so use of Gdn-HSCN will allow the salt-bridging hypothesis to be tested. Urea has a similar structure to Gdn, but is uncharged; thus, urea is to be used to observe how charge affects the association. As well, deuterium labeled Gdn-DCl, Gdn-DSCN and urea were prepared to aid in the analysis of the data. The molecular vibrations of urea and guanidine under various conditions are to be modeled by computer to check the observed vs. calculated vibrations.