Fenton-like Chemistry by a Copper(I) Complex and H<sub>2</sub>O<sub>2</sub> Relevant to Enzyme Peroxygenase C–H Hydroxylation
Bohee Kim, Magdalene T. Brueggemeyer, Wesley J. Transue, Younwoo Park, Jaeheung Cho, Maxime A. Siegler, Edward I. Solomon, Kenneth D. Karlin
Abstract
Lytic polysaccharide monooxygenases have received significant attention as catalytic convertors of biomass to biofuel. Recent studies suggest that its peroxygenase activity (i.e., using H 2 O 2 as an oxidant) is more important than its monooxygenase functionality. Here, we describe new insights into peroxygenase activity, with a copper(I) complex reacting with H 2 O 2 leading to site-specific ligand–substrate C–H hydroxylation. [Cu I (TMG 3 tren)] + ( 1 ) (TMG 3 tren = 1,1,1-Tris{2-[ N 2 -(1,1,3,3-tetramethylguanidino)]ethyl}amine) and a dry source of hydrogen peroxide, ( o -Tol 3 P═O·H 2 O 2 ) 2 react in the stoichiometry, [Cu I (TMG 3 tren)] + + H 2 O 2 → [Cu I (TMG 3 tren-OH)] + + H 2 O, wherein a ligand N -methyl group undergoes hydroxylation giving TMG 3 tren-OH. Furthermore, Fenton-type chemistry (Cu I + H 2 O 2 → Cu II -OH + ·OH) is displayed, in which (i) a Cu(II)-OH complex could be detected during the reaction and it could be separately isolated and characterized crystallographically and (ii) hydroxyl radical (·OH) scavengers either quenched the ligand hydroxylation reaction and/or (iii) captured the ·OH produced.