Fig. 2

Verification of LPMO activity. Full-length mgLPMO10 or mgLPMO10^CD was incubated with 5 g/L PASC or 10 g/L Avicel in 50 mM sodium phosphate buffer (pH 6.0) supplemented with 1 mM ascorbic acid at 60 °C for 24 h. The supernatant was subjected to analysis by MALDI-ToF (PASC samples) for both mgLPMO10 variants (a) and HPAEC-PAD (Avicel samples) for full-length mgLPMO10 (b). The peaks of the hexamer cluster are denoted by arrows and show the sodium adduct of native cellohexaose [Glc₆ + Na]⁺ and two larger peaks that represent sodium adducts of C1-oxidized cellohexaose (aldonic acid), namely [Glc₅Glc1A + Na]⁺ and [Glc₅Glc1A − H + 2Na]⁺. Note that the 1,5-δ-lactone (m/z − 2 species) is also visible at 1011.9, labeled [Glc₅-Lac + Na]⁺. Of note, the spectrum shows a series of minor signals (984, 1145, 1307, grey-labeled masses) differing by one glucose (162 m/z) that represent products of unknown nature. No products were observed for a reaction with only PASC and AscA, and neither for a reaction with PASC and the LPMO but in absence of AscA (grey spectrum). The HPAEC chromatogram for mgLPMO10 shows similar product profile as the well-characterized ScLPMO10C with C1-oxidized cello-oligomers ranging from DP 2-7. No C4-oxidized products, that have longer retention times [18], were detected