Iron and copper ions are ubiquitous in nature and serve a variety of important biological functions. My presentation will focus on the characterization of (1) the first biologically-relevant oxoiron(V) model complex and (2) a Cu/O2 intermediate in the mononuclear copper enzyme Formylglycine-Generating Enzyme (FGE). In both cases, we have been able to utilize spectroscopic insight to characterize novel, fleeting intermediates and to understand how they fit into proposed reaction mechanisms.

(1) Oxoiron(V) species are fleeting intermediates that are postulated to be involved in some of the most difficult oxidative transformations in biology. Using a biomimetic analog, we employed resonance Raman, electron paramagnetic resonance, and Mössbauer spectroscopies in conjunction with calibrated DFT computations to elucidate key structural and electronic properties. We were able to attribute its highly anisotropic hyperfine parameters and unusual spectroscopic features to an iron(V) complex with an axial oxo ligand. Our analysis defines spectroscopic parameters characteristic of perferryl intermediates in biology.

(2) Apart from its importance for sulfatase activity, FGE also serves as a powerful tool for protein engineering because of its ability to introduce aldehyde functional groups into recombinant proteins. Together with my collaborators, we have used high-energy X-ray techniques to spectroscopically define the unique copper active site in the absence and presence of its functional peptide substrate. Furthermore, we now have evidence for key intermediates along the O2-reaction pathway. With this crucial insight in hand, we have a more complete understanding of how FGE utilizes its unique mononuclear copper active site to activate O2, initiate reaction with substrate, and generate the Cα-formylglycine product.




Katlyn Meier, PhD. (Stanford University)