Copper Complexes as Bioinspired Models for Lytic Polysaccharide Monooxygenases

Abstract

We report here two copper complexes as first functional models for lytic polysaccharide monooxygenases, mononuclear copper-containing enzymes involved in recalcitrant polysaccharide breakdown. These complexes feature structural and spectroscopic properties similar to those of the enzyme. In addition, they catalyze oxidative cleavage of the model substrate p-nitrophenyl-β-d-glucopyranoside. More importantly, a particularly stable copper(II) hydroperoxide intermediate is detected in the reaction conditions.

Oxygen Activation by Cu LPMOs in Recalcitrant Carbohydrate Polysaccharide Conversion to Monomer Sugars

“…269 In parallel, Concia et al showed that tridentate complexes with both N -[(1-methyl-1 H -imidazol-2-yl)-methylene]-2-pyridineethanamine (L AM ) and N -[(1-methyl-1 H -imidazol-2-yl)methylene]-2-pyridineethanimine (L IM ) produced stable Cu(II)–hydroperoxide complexes that react with a model substrate ( p -nitrophenyl- β -D-glycopyranoside) of cellulose at room temperature. 296 The role(s) of this intermediate, however, were not uncoupled from alternative scenarios involving copper-generated radicals. Regardless, these data provide insight into a potential mechanism for LPMO function where H 2 O 2 is utilized as a cosubstrate.…”

Copper-Promoted Functionalization of Organic Molecules: from Biologically Relevant Cu/O2 Model Systems to Organometallic Transformations

“…Simaan has recently reported the LPMO-like reactivity of mononuclear Cu(II) complexes using H 2 O 2 as oxidant (Figure 35). 185 These copper complexes catalyzed the oxidative cleavage of 4-nitrophenyl- β - D -glucopyronaside via C–H oxidation of the 1-position of the glucose derivative to produce glucolactone and 4-NO 2 -phenolate (observed and quantified by UV–vis). It was suggested that the LCu II reacted with H 2 O 2 under aqueous conditions to form a mononuclear LCu II (OOH) species that could be characterized by UV–vis ( λ : 305 nm) and EPR spectroscopy.…”

Metal-Bound Nitrate Anion as an Acceptor for Halogen Bonds in Mono-Halopyridine-Copper(II) Nitrate Complexes

“…For the solvated systems, solvent molecule is directly coordinated to the Cu(II)-centre along with two nitrates and two halopyridines thereby transforming the distorted octahedral to distorted pentagonal bipyramid geometry -a coordination geometry frequently reported for Cu(II)-complexes. [34][35][36][37][38] In the…”