Biological catalysis underpins all cellular processes and is reliant on the activity of many different enzymes, whose functions allow complex chemistry to be performed in water at ambient temperatures. We use a combination of X-ray crystallography, electron microscopy, biophysical methods and biochemistry to investigate how a variety of different enzymes work. Areas of interest include the function of metalloproteins (particularly hydrogenases), protein-DNA interactions and the role of ubiquitin ligases during development .
[NiFe]-Hydrogenases are complex metalloenzymes containing nickel and iron atoms at their active site, which allow bacteria to use hydrogen as an energy source. This is achieved by enzymatic splitting of hydrogen gas into protons and electrons. We use structural biology, electrochemistry and IR spectroscopy (in collaboration with Professors Fraser Armstrong and Kylie Vincent, University of Oxford) to understand how the enzyme influences the properties of nickel and iron ions bound within the protein in order to split or produce hydrogen. Analysis of variant proteins containing mutated amino acids at the active site of the protein has allowed us to propose a novel mechanism for how [NiFe]-hydrogenases can achieve this.
We are pioneering the technique of single-crystal IR spectroscopy coupled with electrochemical control of the redox state of the crystallised protein to trap and determine the structures of intermediates of the catalytic cycle. This will allow a complete understanding of how these enzymes function in the cell. The active site may also act as inspiration for the design of novel, inexpensive chemical catalysts based on Ni/Fe that will be essential for the success of the future hydrogen economy.