Fig. 4

Analyses of the substrate specificity of XynA. a Reducing sugar analyses of XynA on nature substrates with different glycosidic linkages. XynA (0.5 μM) was incubated separately with different substrates (5 mg/mL); the reactions were performed at pH 6.0 and 65 °C for 30 min. Bars denote the standard errors for three independent experiments. b Determination of the specific activities of XynA with xylans, pNP-linked sugars, and cellulose substrates. The final concentrations for all polysaccharide substrates were 10 mg/mL, while the concentrations of pNPX, pNPG, and pNPC were 1 mM. The reducing sugars were measured using the pHBAH method, and pNP was measured spectrophotometrically at 410 nm. c HPAEC-PAD analyses of the hydrolytic products of hardwood xylans (birchwood xylan and beechwood xylan) by XynA. The final concentration of substrate and XynA was 10 mg/mL and 0.5 μM, respectively. The hydrolysis was performed at pH 6.0 and 65 °C for 16 h. X1–X6 were mixed and analyzed to serve as standards for the assignment of the released products. d HPAEC-PAD analysis of the hydrolytic products of Avicel by XynA. The final concentration of substrate and XynA was 10 mg/mL and 10 μM, respectively. The hydrolysis was performed at pH 6.0 and 65 °C for 16 h. G1–G6 were mixed and analyzed to serve as standards