Substitutions of sulfonatocalix[4]arenes that lead to applications in biomolecular recognition and give rise to novel self-association phenomena
Date
2014-12-23
Authors
Garnett, Graham
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Abstract
The epigenetic post-translational modifications (PTMs) of histone proteins are numerous and have an important role in regulating cellular development. Molecular recognition elements that can bind directly to epigenetic PTMs have previously been developed. The most synthetically accessible of these are a family of molecules called monoaryl-trisulfonate calix[4]arenes. The initial goal of this thesis was to develop research tools consisting of these asymmetrically-derivatized calixarenes immobilized onto a solid resin for the purpose of enrichment of PTM-bearing species. Seven novel resin-immobilized calixarene reagents were created and employed in batch-wise pulldown experiments, as well as chromatographic separations. These experiments produced mixed results: poor efficacy was demonstrated in batch-binding experiments but total separation of certain PTM bearing peptides was achieved in a chromatographic approach. During these studies, a subset of these calixarenes were found to undergo self-association in water in a fashion not previously observed for calixarenes. Secondary goals of the thesis were to create new examples of this self-associating motif, and to characterize and develop structure-function relationships for their assemblies. Eight new self-associating calixarenes were developed and characterized extensively by 1H NMR, isothermal titration calorimetry (ITC), and X-ray crystallography. Self-association was shown to be enthalpically driven with Kd values ranging from 1-20 mM. The dimeric assembly behaviours were remarkably consistent across many different family members, and were shown to persist even in highly competitive media like mock blood and urine. This system represents a novel class of ordered calixarenes assemblies that operate in biological media.
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Keywords
Kme3, calixarene, self-association, affinity chromatography