Beschreibung:
<jats:title>Significance</jats:title>
<jats:p>Biomass decomposition by microorganisms relies on a battery of enzymes, of which lytic polysaccharide monooxygenases (LPMOs) constitute a central player. LPMOs are notably able to disrupt the abundant recalcitrant carbohydrates cellulose and chitin and thus increase the overall rate of their degradation. It has recently been demonstrated that LPMOs prefer hydrogen peroxide over molecular oxygen to oxidize and cleave their substrates. Here, we explain through molecular simulations and experiments how a chitin-active LPMO activates hydrogen peroxide and catalyzes substrate hydrogen abstraction. Thereby, we reveal the molecular details of this unusual bioinorganic chemistry, which is of high relevance for the understanding of pathogenesis-defense mechanisms and biomass turnover.</jats:p>