Electron transfer is one of the most crucial reactions in biochemistry and the efficient and controlled transfer of electrons is crucial to living organisms. Metalloproteins with copper centres are particularly effective at performing electron transfer and understanding the link between structure and function of proteins lies at the heart of much biochemical and biophysical research. We propose a programme of research that interleaves novel theoretical developments (at Nottingham and Warwick) with new experiments (at Nottingham) to build a detailed understanding of the function of blue copper proteins, such as plastocyanin. Model complexes of the active site will be generated in the gas-phase and their spectroscopy measured. Adopting this approach will allow the oxidised and reduced forms of the active site to be studied directly, and will furnish information on how the presence of the coordinating ligands modulates the behaviour of the active site. Building on this, we plan to design complexes with tunable spectroscopic properties. The application of quantum chemical methods to study biological processes is without doubt an area of research that will grow rapidly in the near future. Molecular dynamics simulations within a quantum mechanics/molecular mechanics framework will be performed for the oxidised and reduced forms of the protein, and extended to the ligand-to-metal charge transfer state of the oxidised form. These simulations will form the basis for the development of force fields that will be used to study the charge transfer process and establish the form of the entatic state of the protein directly.