Fig. 4

XacAbf51 hydrolyzes internal mono- and di-substitutions of AXOS. a Mass spectra of XA²⁺³XX (2³, 3³-di-α-l-arabinofuranosyl-xylotetraose) after 0, 10 and 15 min of reaction with XacAbf51 (15 µg mL⁻¹) at 50 °C, pH 5.5, using 10 mM substrate. Boxed peaks correspond to the sodiated forms of the substrate XA²⁺³XX (m z⁻¹ = 810 + 23 (Na⁺) = 833) and the product xylotetraose (XXXX, m/z = 546 + 23 (Na⁺) = 569). b Kinetic parameters of XA²⁺³XX hydrolysis by XacAbf51 (15 µg mL⁻¹) at 50 °C, pH 5.5, assessed by mass spectrometry in triplicate. c Mass spectra of XA³XX (3³-α-l-arabinofuranosyl-xylotetraose) after 0, 10 and 15 min of reaction with XacAbf51 in the same conditions described in (a). Boxed peaks correspond to the sodiated forms of the substrate XA³XX (m z⁻¹ = 678 + 23 (Na⁺) = 701) and the product XXXX (m/z = 546 + 23 (Na⁺) = 569). d Kinetic parameters of XA³XX hydrolysis by XacAbf51 (15 µg mL⁻¹) at 50 °C, pH 5.5, assessed by mass spectrometry in triplicate. Error bar represents standard deviations of the mean