Oxygen Activation at the Active Site of a Fungal Lytic Polysaccharide Monooxygenase. Issue 3 (22nd December 2016)

• Record Type: Journal Article
• Authors: O'Dell, William B.; Agarwal, Pratul K.; Meilleur, Flora
• Is Part Of: Angewandte Chemie international edition. Volume 56:Issue 3(2017)
• Page Start: 767
• Page End: 770
• Publication Date: 2016-12-22
• Subjects: copper -- oxidoreductases -- oxygen activation -- polysaccharide monooxygenases -- protein structures; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.201610502
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Lytic polysaccharide monooxygenases have attracted vast attention owing to their abilities to disrupt glycosidic bonds via oxidation instead of hydrolysis and to enhance enzymatic digestion of recalcitrant substrates including chitin and cellulose. We have determined high‐resolution X‐ray crystal structures of an enzyme from Neurospora crassa in the resting state and of a copper(II) dioxo intermediate complex formed in the absence of substrate. X‐ray crystal structures also revealed "pre‐bound" molecular oxygen adjacent to the active site. An examination of protonation states enabled by neutron crystallography and density functional theory calculations identified a role for a conserved histidine in promoting oxygen activation. These results provide a new structural description of oxygen activation by substrate free lytic polysaccharide monooxygenases and provide insights that can be extended to reactivity in the enzyme–substrate complex. Abstract : In bound O2 : X‐ray crystallography produces the first structure of a lytic polysaccharide monooxygenase (LPMO) enzyme with an activated dioxo species bound in the plane of the histidine brace (see structures, right: O red, Cu copper, N blue, C green). A "pre‐binding" site for molecular oxygen is also identified and characterized with neutron protein crystallography (left) and DFT calculations.