Recent advances in enzyme technology for the degradation of cellulose, a key component of lignocellulosic biomass, have led to the discovery of novel enzymes classified as CBM33 and GH61. These enzymes catalyze oxidative cleavage of polysaccharides, enhancing the efficiency of classical hydrolytic enzymes by acting on the surfaces of insoluble substrates. They introduce chain breaks in polysaccharide chains without requiring the chains to be extracted from their crystalline matrix. These enzymes are particularly effective in breaking down cellulose, which is highly recalcitrant and challenging to process. Lignocellulosic biomass consists of cellulose, hemicellulose, and lignin, with cellulose being the most abundant and recalcitrant polysaccharide. Traditional enzyme systems for degrading cellulose involve endo-acting and exo-acting enzymes, but recent studies have shown that CBM33 and GH61 enzymes may offer a more efficient approach. These enzymes, which are found in various organisms including bacteria and fungi, have flat substrate-binding surfaces and use an oxidative mechanism involving divalent metal ions and an electron donor. The discovery of these enzymes has significant implications for the future of biorefineries and bioeconomy, as they can improve the efficiency of enzymatic conversion of biomass. These enzymes are copper-dependent and can generate oxidized sugars such as aldonic acids, which may have different effects on enzyme activity and product inhibition. The potential of these enzymes for biomass conversion is supported by recent studies showing their expression is induced by cellulose and co-regulated with cellulases. Despite their potential, challenges remain in understanding the full mechanism of these enzymes and their application in industrial settings. Further research is needed to optimize their use in enzymatic saccharification and to explore their broader applications in biomass processing. The discovery of these enzymes represents a new paradigm in the enzymatic degradation of cellulose, offering new possibilities for improving the efficiency and sustainability of biofuel production.Recent advances in enzyme technology for the degradation of cellulose, a key component of lignocellulosic biomass, have led to the discovery of novel enzymes classified as CBM33 and GH61. These enzymes catalyze oxidative cleavage of polysaccharides, enhancing the efficiency of classical hydrolytic enzymes by acting on the surfaces of insoluble substrates. They introduce chain breaks in polysaccharide chains without requiring the chains to be extracted from their crystalline matrix. These enzymes are particularly effective in breaking down cellulose, which is highly recalcitrant and challenging to process. Lignocellulosic biomass consists of cellulose, hemicellulose, and lignin, with cellulose being the most abundant and recalcitrant polysaccharide. Traditional enzyme systems for degrading cellulose involve endo-acting and exo-acting enzymes, but recent studies have shown that CBM33 and GH61 enzymes may offer a more efficient approach. These enzymes, which are found in various organisms including bacteria and fungi, have flat substrate-binding surfaces and use an oxidative mechanism involving divalent metal ions and an electron donor. The discovery of these enzymes has significant implications for the future of biorefineries and bioeconomy, as they can improve the efficiency of enzymatic conversion of biomass. These enzymes are copper-dependent and can generate oxidized sugars such as aldonic acids, which may have different effects on enzyme activity and product inhibition. The potential of these enzymes for biomass conversion is supported by recent studies showing their expression is induced by cellulose and co-regulated with cellulases. Despite their potential, challenges remain in understanding the full mechanism of these enzymes and their application in industrial settings. Further research is needed to optimize their use in enzymatic saccharification and to explore their broader applications in biomass processing. The discovery of these enzymes represents a new paradigm in the enzymatic degradation of cellulose, offering new possibilities for improving the efficiency and sustainability of biofuel production.