Enhanced Biomass Degradation by Polysaccharide Monooxygenases

Abstract

The degradation of cellulose is typically described as a process that relies solely on the action of hydrolytic enzymes. Although it had been suggested that this picture was incomplete, no additional activities could be identified during many decades of intensive research. Very recently, however, the discovery of polysaccharide monooxygenases (PMO) shed new light on the degradation process and paved the way for a much more efficient use of renewable resources. Indeed, PMOs were found to render cellulose chains more accessible for hydrolytic enzymes by disrupting the substrate's crystal packing through an oxidative cleavage reaction. These findings constitute a major breakthrough in biomass research but are still not completely understood. In this chapter, an up-to-date overview will be presented of our current knowledge about the function, structure and mechanism of this new class of enzymes.

Kinetic analysis of amino acid radicals formed in H 2 O 2 -driven Cu I LPMO reoxidation implicates dominant homolytic reactivity

“…H eightened recent attention on lytic polysaccharide monooxygenases (LPMOs) has stemmed from their ability to produce monomeric sugars through degradation of complex natural carbohydrates such as starch (1), cellulose (2), and chitin (3)-a process with significant chemical and industrial applications (4)(5)(6). This class of metalloenzymes is characterized by a mononuclear copper active site ligated by an unusual "His-brace" motif (7), comprising a bidentate histidine bound through both the imidazole ring and backbone N-terminal amine ( Fig.…”