The structural elucidation and characterisation of biomolecular complexes is crucial to both the agrichemical and pharmaceutical industries. Understanding the specific interactions that govern protein-inhibitor interactions enables more intelligent design of herbicide and drug candidates. While there are powerful tools currently available to obtain protein-inhibitor structures, they alone cannot answer the questions posed by protein-inhibitor binding. EVV 2DIR spectroscopy is a novel technique capable of detecting protein-inhibitor interactions that can provide structural information complementary to that of other methods (such as direct measurement of hydrogen bond formation) to build up a more complete picture of protein-inhibitor binding.
This thesis presents the first EVV 2DIR spectra of plant protein-inhibitor complexes, comprised of the herbicide target 4-Hydroxyphenylpyruvic acid dioxygenase (HPPD) bound to various herbicide candidates. Difference spectra of HPPD and project compound 329 consistently showed one cross-peak that could be tentatively assigned to coupled vibrational modes specific to protein-inhibitor binding. The data presented exhibits the capability of EVV 2DIR spectroscopy to detect protein-inhibitor binding for plant systems and demonstrates its potential as a tool for the screening of herbicide candidates.
The first EVV 2DIR spectra for the peptide amyloid beta (1-40) both with and without Cu(II) and Zn(II) are also presented. Comparison of the spectra reveals changes indicative of the literature observations that amyloid beta (1-40) forms rigid fibrils at an acidic pH, and that the addition of Cu(II) and Zn(II) disrupts and retards fibril formation. Tentative assignments were made for the resultant spectra, however a lack of corresponding calculated EVV 2DIR spectra (previously produced from vibrational modes elucidated via DFT calculations) made definitive assignment of such complex spectra not possible. There are currently no published structures of amyloid beta (1-40) with Cu(II), so accompanying calculated spectra enabling conclusive assignments may reveal significant structural insights into the coordination of copper by amyloid beta in the future.Open Acces
