Fig. 4From: Expression and secretion of a lytic polysaccharide monooxygenase by a fast-growing cyanobacteriumS. elongatus UTEX 2973 TfAA10A activity assays. a Amplex red assay. The assay was performed in 20 mM sodium phosphate buffer, pH 6.0. All reaction mixtures contained 100 µM EDTA, 80 µM ascorbate, 50 µM Ampliflu red, 20 U mL−1 HRP and 1 µg purified and reconstituted TfAA10A. The negative control omitted the enzyme. The buffer control sample contained only 20 mM sodium phosphate buffer, pH 6.0. Resorufin fluorescence was recorded with an excitation and emission wavelength of 557 nm and 583 nm, respectively. All experiments were carried out at 37 °C. Results are an average of three replicates and error bars represent the standard deviation. Nonvisible error bars are smaller than the data symbol. b PASC oxidation by TfAA10A. TfAA10A catalyzed oxidation of PASC was performed in 50 mM phosphate buffer (pH 7.5). All reaction mixtures contained 2 mM ascorbate, 0.75% w/v PASC and 2 µg purified and reconstituted TfAA10A. The negative control omitted the enzyme. Reactions were carried out at 50 °C for 24 h. Peak assignments are based on cello-oligosaccharide standards and inferences from previous studies [45, 46]. DP—degree of polymerization. DP3–DP6—commercially available native oligosaccharide standards. DP2ox–DP6ox—synthesized oxidized oligosaccharide standards. DP3—cellotriose, DP4—cellotetraose, DP5—cellopentaose and DP6—cellohexaose, DP2ox—cellobionic acid, DP3ox—cellotrionic acid, DP4ox—cellotetraonic acid, DP5ox—cellopentaonic acid, DP6ox—cellohexaonic acid and DP7ox—celloeptaonic acid. Results are an average of three replicates. Full chromatogram can be found in Additional file 1: Figure S5Back to article page