The impact of reductants on the catalytic efficiency of a lytic polysaccharide monooxygenase and the special role of dehydroascorbic acid

© 2021 The Authors. FEBS Letters published by John Wiley & Sons Ltd on behalf of Federation of European Biochemical Societies..

Monocopper lytic polysaccharide monooxygenases (LPMOs) catalyse oxidative cleavage of glycosidic bonds in a reductant-dependent reaction. Recent studies indicate that LPMOs, rather than being O2 -dependent monooxygenases, are H2 O2 -dependent peroxygenases. Here, we describe SscLPMO10B, a novel LPMO from the phytopathogenic bacterium Streptomyces scabies and address links between this enzyme's catalytic rate and in situ hydrogen peroxide production in the presence of ascorbic acid, gallic acid and l-cysteine. Studies of Avicel degradation showed a clear correlation between the catalytic rate of SscLPMO10B and the rate of H2 O2 generation in the reaction mixture. We also assessed the impact of oxidised ascorbic acid, dehydroascorbic acid (DHA), on LPMO activity, since DHA, which is not considered a reductant, was recently reported to drive LPMO reactions. Kinetic studies, combined with NMR analysis, showed that DHA is unstable and converts into multiple derivatives, some of which are redox active and can fuel the LPMO reaction by reducing the active site copper and promoting H2 O2 production. These results show that the apparent monooxygenase activity observed in SscLPMO10B reactions without exogenously added H2 O2 reflects a peroxygenase reaction.

Medienart:

E-Artikel

Erscheinungsjahr:

2022

Erschienen:

2022

Enthalten in:

Zur Gesamtaufnahme - volume:596

Enthalten in:

FEBS letters - 596(2022), 1 vom: 29. Jan., Seite 53-70

Sprache:

Englisch

Beteiligte Personen:

Stepnov, Anton A [VerfasserIn]
Christensen, Idd A [VerfasserIn]
Forsberg, Zarah [VerfasserIn]
Aachmann, Finn L [VerfasserIn]
Courtade, Gaston [VerfasserIn]
Eijsink, Vincent G H [VerfasserIn]

Links:

Volltext

Themen:

Dehydroascorbic Acid
Dehydroascorbic acid
Enzyme kinetics
Hydrogen peroxide
Journal Article
LPMO
NMR
Research Support, Non-U.S. Gov't
Y2Z3ZTP9UM

Anmerkungen:

Date Completed 10.02.2022

Date Revised 10.02.2022

published: Print-Electronic

Citation Status MEDLINE

doi:

10.1002/1873-3468.14246

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM333827538