Oxidative breakdown of polysaccharides

A method for oxidizing a polysaccharide comprising the steps:

• (a) providing a polysaccharide, and
• (b) incubating said polysaccharide with a composition comprising a lytic polysaccharide monooxygenase enzyme (E.C. 1.14.99.-) and an auxiliary activity family 7 (AA7) enzyme,
• wherein said AA7 enzyme comprises (I) dehydrogenase activity (E.C. 1.1.1.-) and (II) gluco-oligosaccharide oxidase activity (E.C. 1.1.3.-) for oxidizing reducing end glycosyl residues of monosaccharides, oligosaccharides, and/or polysaccharides, and wherein the amino acid sequence of said AA7 enzyme in pairwise alignment with polypeptide SEQ ID NO.:
• 1, comprises
• (i) a catalytic base tyrosine (Y) at a first amino acid position corresponding to amino acid residue Y454 of SEQ ID NO.:
• 1,
• (ii) an arginine (R) at a second amino acid position corresponding to amino acid residue R156 of SEQ ID NO.:
• 1,
• (iii) an amino acid residue other than histidine (H) at a third amino acid position corresponding to amino acid residue S165 of SEQ ID NO.:
• 1, and
• (iv) an amino acid residue other than cysteine (C) at a fourth amino acid position corresponding to amino acid residue G157 of SEQ ID NO.:
• 1 or an amino acid residue other than histidine (H) at a fifth amino acid position corresponding to amino acid residue H97 of SEQ ID NO.:
• 1,
• wherein said pairwise sequence alignment is performed using scoring matrix:
• blosum62, gap opening penalty:
• 1.53, and gap extension penalty 0.123, and wherein the amino acid sequence of said AA7 furthermore has at least 78% sequence identity to SEQ ID NO.:
• 1.