Chemistry Seminar Presented by Prof. Paul Walton: "The active sites of copper oxygenases and their reactivity with H2O2"

The Department of Chemistry is excited to host Paul Walton (University of York, UK) for the annual Chem Connect Lecture. To learn more about Professor Walton's work, please visit https://www.york.ac.uk/chemistry/staff/academic/t-z/pwalton/ Lytic polysaccharide monooxygenases (LPMOs) are relatively recently discovered enzymes that catalyse the oxidation of polysaccharides, leading to chain cleavage. LPMOs has transformed our understanding of biomass degradation, and-moreover-are now critical components in the enzymatic breakdown of biomass in the second generation bioethanol industry. We and others have also recently shown that LPMOs are key virulence factors in major plant diseases. We have also examined the action of oxidizing agents on the enzyme which has been shown to enhance the activity of the enzymes on saccharidic substrates, but also lead to rapid inactivation of the enzyme, presumably through protein oxidation. In this talk, in addition to a description of the structure and reactivity of LPMOs, I will show that the use of UV/vis, CD, XAS, EPR, MCD, MS and resonance Raman spectroscopies augmented with DFT calculations, reveals that one of the products of protein oxidation in an AA9 LPMO is a long-lived ground-state singlet Cu(II)-tyrosyl species, which is inactive for the oxidation of saccharidic substrates. I will also show that this state evolves from an intermediate Cu(II)...tyrosyl triplet species via an open-shell singlet Cu(II)-histidyl radical-the first such species to be characterized in a protein. Hosted by Kathy Franz