TECHNOLOGY FOCUS - BIOTECHNOLOGY - Recombinant method (disclosed): The non-naturally occurring polypeptide (A1) is prepared by using recombinant method. Preferred Polypeptide: The polypeptide (A1) further optionally comprises a third domain having a dehydrogenase domain. Preferred Composition: In the composition (C1), the recombinant GH61 polypeptide comprises a polypeptide of the NCU02240/NCU01050 clade. The recombinant GH61 polypeptide comprises SEQ ID NO: 24, as available on WIPO website (NCU02240), SEQ ID NO: 30, as available on WIPO website (NCU01050), (SEQ ID NO: 26) (NCU07898), (SEQ ID NO: 28) (NCU08760), or (SEQ ID NO: 90) (NCU00836). The recombinant GH61 polypeptide comprises the motif H-X(4-8)-Q-X-Y. The recombinant CDH-heme domain polypeptide containing a CBM comprises (SEQ ID NO: 32) (Neurospora crassa CDH-1) or (SEQ ID NO: 46) (Myceliophthora thermophile CDH-1). The recombinant CDH-heme domain polypeptide containing a CBM is a non-naturally occurring polypeptide, comprising a first domain and a second domain. The recombinant CDH-heme domain polypeptide containing a CBM is a non-naturally occurring polypeptide, comprising a first domain, a second domain, and a third domain. The composition (C2) further comprises a GH61 polypeptide; and at least one cellulase. In the composition (C2), the first polypeptide and the second polypeptide interact through a leucine zipper motif. The CDH-heme domain comprises an amino acid sequence selected from SEQ ID NO: 70, as available on WIPO website (Neurospora crassa CDH-1 heme domain); SEQ ID NO: 76, as available on WIPO website (Neurospora crassa CDH-2 heme domain); SEQ ID NO: 80, as available on WIPO website (Myceliophthora thermophile CDH-1 heme domain); and SEQ ID NO: 86, as available on WIPO website (Myceliophthora thermophile CDH-2 heme domain), and where the CBM comprises an amino acid sequence of SEQ ID NO: 74, as available on WIPO website (Neurospora crassa CDH-1 CBM domain) or SEQ ID NO: 84, as available on WIPO website (Myceliophthora thermophile CDH-1 CBM domain). In the composition (C3), at least 90% of the GH61 polypeptides are bound to a copper atom. The recombinant GH61 polypeptides comprises i) a polypeptide of the NCU2240/NCU01050 clade, or ii) an amino acid sequence selected from SEQ ID NO: 90 (NCU00836), SEQ ID NO: 26 (NCU07898), or SEQ ID NO: 28 (NCU08760).X=any amino acid;Q' and Y'=residues important for binding copper, substrate binding/positioning/acting as a general acid;H'=motif corresponds to residue 153 of the NCU02240 polypeptide after the signal sequence is cleaved or Q'.Preferred Method: In the method (M1), the Lewis acid is a recombinant GH61 polypeptide, and the molecule comprising a heme group and containing a CBM is a recombinant CDH-heme domain polypeptide containing a CBM. In the method (M2), the biomass is subjected to a preprocessing step. In the method (M3), at least 50 (at least 90)% of the GH61 polypeptides are bound to a copper atom. In the method (M4), the cell is cultured in a media that contains 100-800 mu M copper. In the method (M5), the concentration of copper in the reaction mixture is 1-50 mu M. EXAMPLE - No suitable example given.