Protein-protein and ligand-protein interactions as well as the effect of temperature and applied pressure on protein conformation were investigated by Fourier transform infrared (FTIR) spectroscopy with the use of Fourier self-deconvolution, Fourier derivative, and two-dimensional correlation techniques. The effect of the binding of biotin to avidin on the conformation of the protein was examined. At a biotin concentration of 0.05% (w/v), avidin was stabilized against thermal and pressure-induced denaturation. The IR spectra of avidin recorded as a function of increasing hydrostatic pressure in the presence and the absence of biotin indicated that, in the presence of biotin, avidin adopts a very compact structure in solution. The 2D correlation analysis of the infrared spectra of avidin recorded as a function of increasing temperature over the range of 25--95°C revealed that the protein unfolded via different pathways in the presence and the absence of biotin. Furthermore, the thermally induced conformational changes observed in the absence of biotin were irreversible upon cooling of the protein solution, owing to aggregation of the thermally unfolded protein, whereas in the presence of biotin the protein unfolded and refolded via the same pathway. Variable-temperature FTIR spectroscopy and 2D correlation analysis were also employed to examine correlations between absorptions in the amide I and amide III regions in the spectra of four proteins. The results suggested that the band at 1284 cm-1 in the amide III region may be tentatively assigned to the intermolecular beta-sheet structure formed upon aggregation of thermally unfolded protein. FTIR studies were also conducted to investigate the interaction between the catalytic and regulatory subunits of the enzyme ATCase. The secondary structure of the ATCase holoenzyme was stable up to 60°C. The isolated regulatory subunit denatured at approximately 47°C while the isolated catalytic subunit was thermall
| Identifer | oai:union.ndltd.org:LACETR/oai:collectionscanada.gc.ca:QMM.36616 |
| Date | January 2000 |
| Creators | Ismoyo, Fenny. |
| Contributors | Ismail, Ashraf A. (advisor) |
| Publisher | McGill University |
| Source Sets | Library and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada |
| Language | English |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Format | application/pdf |
| Coverage | Doctor of Philosophy (Department of Food Science and Agricultural Chemistry.) |
| Rights | All items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated. |
| Relation | alephsysno: 001763512, proquestno: NQ64582, Theses scanned by UMI/ProQuest. |
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