Designing a chemical “toolbox” for the efficient inhibition of metalloenzymes

Metalloenzymes, enzymes that utilise a metal ion within their active site for their enzymatic activity, make up a significant portion of known enzymes. In fact, literature suggests that approximately 40 – 50% of all known enzymes may be classed as metalloenzymes. Many of these are implicated in disease and drug resistance. Despite this, there is a significant lack of small-molecule therapeutics focused upon metalloenzyme inhibition. Metallo-β-lactamases are a family of metalloenzymes that can be found in bacteria. These enzymes cause drug resistance against β-lactam antibiotics, such as penicillin, to emerge in these bacteria. Currently there are no metallo-β-lactamase inhibitors available for clinical use. As such, the World Health Organisation has noted this gap as being a priority for development. This thesis describes attempts to develop new metal-binding functionalities and to extend the evidence of known functionalities in targeting metallo-β-lactamases. What is learned from this work can then be used to inform medicinal chemists of effective metal-binding moieties when developing small-molecule therapeutics for other metalloenzymes. Significant in silico design has been used throughout to aid with the design of molecules based upon targeting Verona integron-encoded metallo-β-lactamase 2. This has led to the extension of knowledge of a previously identified series of thiol-based metallo-β-lactamase inhibitors. Additionally, work on a series of compounds containing a dithiocarboxylate functional group has identified a novel class of inhibitors of these metalloenzymes, showing micromolar activity in assays against a panel of metallo-β-lactamases. Investigation of the stability of the dithiocarboxylate functional group and possible routes of degradation has also been carried out. It is hoped that this work can contribute to the development of potent, selective small-molecule inhibitors of metallo-β-lactamases and other metalloenzymes.