The paper discusses the recent advancements in enzyme technology for the conversion of cellulose, the most abundant and recalcitrant polysaccharide in lignocellulosic biomass. It highlights the discovery of a new type of enzymes, classified as CBM33 and GH61, which catalyze oxidative cleavage of polysaccharides. These enzymes enhance the efficiency of classical hydrolytic enzymes (cellulases) by acting on the surfaces of insoluble substrates, introducing chain breaks without the need to extract the chains from their crystalline matrix. The authors emphasize the importance of these enzymes in future biorefineries and bioeconomy, as they can improve the enzymatic conversion of biomass, reduce enzyme costs, and optimize pretreatment processes. The paper also reviews the structural and functional characteristics of CBM33 and GH61 enzymes, their potential applications, and the challenges that remain in fully understanding and utilizing these novel enzymes.The paper discusses the recent advancements in enzyme technology for the conversion of cellulose, the most abundant and recalcitrant polysaccharide in lignocellulosic biomass. It highlights the discovery of a new type of enzymes, classified as CBM33 and GH61, which catalyze oxidative cleavage of polysaccharides. These enzymes enhance the efficiency of classical hydrolytic enzymes (cellulases) by acting on the surfaces of insoluble substrates, introducing chain breaks without the need to extract the chains from their crystalline matrix. The authors emphasize the importance of these enzymes in future biorefineries and bioeconomy, as they can improve the enzymatic conversion of biomass, reduce enzyme costs, and optimize pretreatment processes. The paper also reviews the structural and functional characteristics of CBM33 and GH61 enzymes, their potential applications, and the challenges that remain in fully understanding and utilizing these novel enzymes.