Alan Carletti, Florian Csarman, Marco Sola, Gianantonio Battistuzzi, Roland Ludwig, Giulia Di Rocco
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引用次数: 0
Abstract
Lytic polysaccharide monooxygenases (LPMOs) are copper enzymes discovered in the past decade. Their importance in the degradation of recalcitrant substrates in sustainable processes is now well established; however, the catalytic peroxygenase mechanism has yet to be fully understood. This is also because the study of reaction kinetics has to deal with multiple variables, including the nature of the substrates, the presence of unwanted side reactions, and the low protein stability in the presence of H2O2 as the cosubstrate. In this work, three bacterial LPMOs from the AA10 family were investigated: Pseudomonas putida AA10 (PpAA10), Streptomyces coelicolor AA10B (ScAA10B), and AA10C (ScAA10C). Their activity against specific substrates was initially evaluated by ATR-FTIR for a qualitative characterization, and then, to determine electrochemically their kinetic constants, an amperometric assay based on the detection of the H2O2 consumption was used. This allowed the determination of turnover numbers (TNs) and total turnover numbers (TTNs) on different substrates. The best performance was obtained with ScAA10C and ScAAA10B on nanocrystalline cellulose with TNs of 3.81 and 2.88 s–1, respectively, and TTNs of 1208 and 735, respectively. PpAA10 is active on β-chitin with a TN of 1.02 s–1 and a TTN of 61, providing valuable insight into their substrate specificity and stability. Although the initial rates were found to be lower than those for fungal LPMOs, the enzyme stability over time increased on more crystalline substrates and in the presence of the carbohydrate-binding module (CBM), yielding activity values comparable to those for fungal LPMOs. Moreover, the presence of the CBM resulted in a more efficient consumption of H2O2 by LPMO, leading to improved enzymatic activity and increased resistance to oxidative inactivation.
期刊介绍:
ACS Catalysis is an esteemed journal that publishes original research in the fields of heterogeneous catalysis, molecular catalysis, and biocatalysis. It offers broad coverage across diverse areas such as life sciences, organometallics and synthesis, photochemistry and electrochemistry, drug discovery and synthesis, materials science, environmental protection, polymer discovery and synthesis, and energy and fuels.
The scope of the journal is to showcase innovative work in various aspects of catalysis. This includes new reactions and novel synthetic approaches utilizing known catalysts, the discovery or modification of new catalysts, elucidation of catalytic mechanisms through cutting-edge investigations, practical enhancements of existing processes, as well as conceptual advances in the field. Contributions to ACS Catalysis can encompass both experimental and theoretical research focused on catalytic molecules, macromolecules, and materials that exhibit catalytic turnover.