Lytic Polysaccharide Monooxygenases in Enzymatic Processing of Lignocellulosic Biomass

Abstract

The discovery of lytic polysaccharide monooxygenases (LPMOs) has revolutionized enzymatic processing of polysaccharides, in particular, recalcitrant insoluble polysaccharides, such as cellulose. These monocopper enzymes display intriguing and unprecedented catalytic chemistry, which make them highly valuable in industrial bioprocessing, but also generate considerable challenges in terms of scientific understanding and optimal implementation. One issue of particular interest is the fact that both molecular oxygen and hydrogen peroxide can drive LPMO reactions. Here, we review recent insights into the catalytic mechanism of LPMOs derived from structural, spectroscopic, and functional studies. We then turn to the question of how one can optimally harness the potential of LPMOs in biomass processing, given the current knowledge of their catalytic mechanism. Finally, we review recent, more applied studies that have addressed the importance of LPMOs in enzymatic conversion of lignocellulosic biomass and discuss how the impact of these powerful enzymes could be improved.

The H2O2-dependent activity of a fungal lytic polysaccharide monooxygenase investigated with a turbidimetric assay

“…A growing body of evidence demonstrates that LPMOs use H 2 O 2 as cosubstrate with a much higher catalytic efficiency than O 2 [26,28,44,51]. While the cosubstrate preference of LPMOs in their native environments is still debated [29] the efficient peroxygenase reactivity may be beneficial in industrial settings to achieve faster biomass depolymerization [52]. (Fig.…”

Controlled depolymerization of cellulose by light-driven lytic polysaccharide oxygenases

“…Subsequently, several experimental studies have confirmed the efficiency of H 2 O 2 -driven LPMO reactions for different LPMO/substrate systems [23][24][25][26][27][28][29] . Furthermore, modeling studies have demonstrated the feasibility of the peroxygenase reaction 23,[30][31][32][33] .…”

Water-soluble chlorophyll-binding proteins from Brassica oleracea allow for stable photobiocatalytic oxidation of cellulose by a lytic polysaccharide monooxygenase

“…1b). Temperature is important for the activity of the LPMOs as most assays are performed at 45-50 °C 41 . The loss of 4.5% photostability is minimal at 50 °C when considering the overall goal is increased activity of TtAA9.…”

“…Another important factor for activity assays is pH. LPMO assays are generally performed around pH 5-7 41 . The WSCP-Chl a showed no change in photostability between pH 5-8 (Fig.…”