7-04: GH61-catalyzed oxidative cleavage of cellulose

Polysaccharide monooxygenases (PMOs), also known as GH61 proteins, are a large family of copper-dependent metalloenzymes expressed by filamentous fungi during growth on lignocellulose.  PMOs have been recently shown to oxidatively cleave cellulose.  The oxidation requires molecular oxygen and a reductant and the reaction mechanism analogous to that of the copper dependent hydroxylases has been proposed.  The oligosaccharides formed through the action of PMOs are oxidized at either the C1 or C4 position, depending on the PMO.  PMOs synergize hydrolases (cellulases) by creating new chain ends on otherwise inaccessible portions of the substrate surface.  Continued studies have focused on the molecular basis of PMO regiospecificity and the mechanism of oxidative cleavage.