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Fig. 1 | Biotechnology for Biofuels

Fig. 1

From: The H2O2-dependent activity of a fungal lytic polysaccharide monooxygenase investigated with a turbidimetric assay

Fig. 1

Activity of LPMO with ascorbate as reductant. a Calibration curve showing the relation between PASC concentration and the turbidity. Assays were performed in 50 mM sodium phosphate buffer, pH 6.0, at 30 °C. The equation for the linear range (0–1.4 mg mL−1 PASC) is given. b Time-dependent turbidity changes of a 0.8 mg mL−1 PASC solution incubated with various LPMO concentrations in the presence (solid lines) and absence (dashed lines) of 1 mM ascorbate. LPMO concentrations are specified above the traces. LPMO and ascorbate were added simultaneously to the assay (black arrows). Traces are vertically shifted by the same increment for better visibility. The extent of the catalytic reaction is indicated by an arrow above the graphs. c Absorbance changes observed in b upon titration of LPMO to PASC in the presence (blue triangles) or absence (black circles) of ascorbate. Dashed lines indicate the addition of LPMO to a buffer solution without PASC in the presence (blue triangles) or absence (black circles) of 1 mM ascorbate. Note that the curves coincide because no apparent changes in optical density were observed. d Degradation of PASC by LPMO measured in an anaerobic glove box. PASC (0.6 mg mL−1) was mixed with 3 µM NcLPMO9C in the absence (green curve) or presence of 2 mM ascorbate (dark and light red curves). For comparison, the experiment was performed under the same conditions (3 µM LPMO and 2 mM ascorbate) under aerobic conditions (dark and light blue curves). A control containing only PASC (0.6 mg mL−1) is shown as a black curve. Note that for technical reasons a different photometer had to be used for this experiment. The equation for the linear range of the calibration curve (0–1 mg mL−1 PASC) was 1.16x + 0.03. The black arrow indicates the addition of LPMO and/or ascorbate. e Reaction rates determined from the initial slopes of the reactions shown in b (blue triangles) and f (black circles). f Reaction of LPMO (3 µM) with various concentrations of ascorbate (solid lines). The arrows indicate the addition of LPMO and ascorbate concentrations are specified above the traces. Identical reactions carried out in the presence of catalase (2000 U mL−1) are indicated as colour-coded dashed lines

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