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SUMMARY:Protection against self-oxidation by copper oxygenases  - Prof. Pa
 ul Walton\, University of York
DTSTART:20221026T093000Z
DTEND:20221026T103000Z
UID:TALK180437@talks.cam.ac.uk
CONTACT:Sharon Connor
DESCRIPTION:Lytic polysaccharide monooxygenases (LPMOs) are relatively rec
 ently discovered enzymes that catalyse the oxidation of polysaccharides\, 
 leading to chain cleavage. LPMOs has transformed our understanding of biom
 ass degradation\, and—moreover—are now critical components in the enzy
 matic breakdown of biomass in the second generation bioethanol industry.1 
 We and others have also recently shown that LPMOs are key virulence factor
 s in major plant diseases.2 Our recent work on LPMOs has examined the acti
 on of oxidizing agents on the enzyme which has been shown to enhance the a
 ctivity of the enzymes on saccharidic substrates\, but also lead to rapid 
 inactivation of the enzyme\, presumably through protein oxidation.3\n\nIn 
 this talk\, in addition to a description of the structure and reactivity o
 f LPMOs\, I will show that the use of UV/vis\, CD\, XAS\, EPR\, MCD\, MS a
 nd resonance Raman spectroscopies augmented with DFT calculations\, reveal
 s that one of the products of protein oxidation in an AA9 LPMO is a long-l
 ived ground-state singlet Cu(II)-tyrosyl species\, which is inactive for t
 he oxidation of saccharidic substrates. I will also show that this state e
 volves from an intermediate Cu(II)…tyrosyl triplet species. Despite its 
 inactive nature\, both Cu(II)-tyrosyl and Cu(II)…tyrosyl species give ne
 w insight into the mechanisms by which LPMOs protect themselves from oxida
 tive inactivation. \n\n[1]K. E. H. Frandsen\, P. H. Walton et al\, Nature 
 Chem. Biol. 298—303 (2016). \n[2]F. Sabbadin\, P. H. Walton et al\, Scie
 nce\, 373\, 774-779 (2021). \n[3]A. Paradisi\, P. H. Walton et al\, J. Am.
  Chem. Soc. 18585—18599 (2019).\n
LOCATION:Unilever Lecture Theatre\, Department of Chemistry\, Lensfield Ro
 ad\, University of Cambridge\, CB2 1EW
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