Probing The Interactions Between Boronic Acids And Cis-diol Containing Biomolecules By Affinity Capillary Electrophoresis

The affinities of boronic acids to cis-diol containing biomolecules have been widely used in biochemical analysis, drug delivery and functional material construction. Sound understanding on the boronic acid-cis-diol containing biomolecule interactions will definitely promote their applications and help to reduce the time spent on finding appropriate boronic acid ligands, while interactions between some new boronic acid ligands and cis-diols and interactions between boronic acids and cis-diol-containing biomolecules including nucleosides and glycoproteins are hard to estimated by traditional methods. Therefore, a convenient method that is applicable to all types of boronic acids and cis-diol-containing compounds is of great importance, especially for cross comparison of different binding species.As a high-performance separation tool, capillary electrophoresis (CE) provides multiple advantages, including high resolution, speed, easy to automation, minute sample amount requirement and the possibility to work under near-physiological conditions. These benefits make CE a powerful tool for the characterization of biomolecular interactions. Although boronic acids have already been frequently used in CE for the separation and detection of sugar or sugar alcohols and separation of nucleosides and glycoproteins, as far as we know, there is no particular work using CE to probe the interactions between boronic acids and cis-diol-containing biomolecules.In this work, we first established an affinity capillary electrophoresis (ACE) method to probe the interactions between boronic acids and cis-diol-containing biomolecules. The validity of the method for a variety of important cis-diol-containing biomolecules and a variety of representative boronic acids was confirmed.Next, binding constants of boronic acids including aryl boronic acids, heterocyclic boronic acids and benzoboroxole with different monosaccharides were determined by the modified ACE method, which shed new light on the affinity characteristics of these boronic acids. In addition, using ACE method, interactions between boronic acid and nucleosides and glycoproteins were assessed in free solution for the first time.Finally, since Chapter2, revealed some special and interesting characters of fluoro-aryl boronic acids, including ultrahigh binding constant at neutral pH, less dependence on surrounding pH, and so onthe association constants of eight different fluoro-phenylboronic acid with fructose, mannose and glucose were determined. Based on these data, the relationships between the affinities and structures of fluoro-aryl boronic acids were investigated, and the effect of ortho-substituted group on boronic acid affinity was assessed.