The "life-span" of lytic polysaccharide monooxygenases (LPMOs) correlates to the number of turnovers in the reductant peroxidase reaction

Copyright © 2023 The Authors. Published by Elsevier Inc. All rights reserved..

Lytic polysaccharide monooxygenases (LPMOs) are monocopper enzymes that degrade the insoluble crystalline polysaccharides cellulose and chitin. Besides the H2O2 cosubstrate, the cleavage of glycosidic bonds by LPMOs depends on the presence of a reductant needed to bring the enzyme into its reduced, catalytically active Cu(I) state. Reduced LPMOs that are not bound to substrate catalyze reductant peroxidase reactions, which may lead to oxidative damage and irreversible inactivation of the enzyme. However, the kinetics of this reaction remain largely unknown, as do possible variations between LPMOs belonging to different families. Here, we describe the kinetic characterization of two fungal family AA9 LPMOs, TrAA9A of Trichoderma reesei and NcAA9C of Neurospora crassa, and two bacterial AA10 LPMOs, ScAA10C of Streptomyces coelicolor and SmAA10A of Serratia marcescens. We found peroxidation of ascorbic acid and methyl-hydroquinone resulted in the same probability of LPMO inactivation (pi), suggesting that inactivation is independent of the nature of the reductant. We showed the fungal enzymes were clearly more resistant toward inactivation, having pi values of less than 0.01, whereas the pi for SmAA10A was an order of magnitude higher. However, the fungal enzymes also showed higher catalytic efficiencies (kcat/KM(H2O2)) for the reductant peroxidase reaction. This inverse linear correlation between the kcat/KM(H2O2) and pi suggests that, although having different life spans in terms of the number of turnovers in the reductant peroxidase reaction, LPMOs that are not bound to substrates have similar half-lives. These findings have not only potential biological but also industrial implications.

Medienart:

E-Artikel

Erscheinungsjahr:

2023

Erschienen:

2023

Enthalten in:

Zur Gesamtaufnahme - volume:299

Enthalten in:

The Journal of biological chemistry - 299(2023), 9 vom: 15. Sept., Seite 105094

Sprache:

Englisch

Beteiligte Personen:

Kuusk, Silja [VerfasserIn]
Eijsink, Vincent G H [VerfasserIn]
Väljamäe, Priit [VerfasserIn]

Links:

Volltext

Themen:

2-methyl-1,4-hydroquinone
332W51E0OC
789U1901C5
Ascorbic Acid
BBX060AN9V
Copper
EC 1.-
EC 1.11.1.-
Hydrogen Peroxide
Hydrogen peroxide
Inactivation
Journal Article
Lytic polysaccharide monooxygenase
Mixed Function Oxygenases
PQ6CK8PD0R
Peroxidase
Peroxidases
Peroxygenase
Polysaccharides
Reducing Agents
Research Support, Non-U.S. Gov't

Anmerkungen:

Date Completed 03.10.2023

Date Revised 03.10.2023

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1016/j.jbc.2023.105094

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM360068928