Figure 4.

The contribution of LPMO activity to the chitinolytic activity of Jd1381. Reaction mixtures contained 1 μm Cu(II) saturated Jd1381, 10 g/liter chitin (α or β, as indicated) and, when indicated in the Fig. 1 mm AscA, in 20 mm BisTris, pH 6.0, and were incubated at 40 °C with shaking at 1000 rpm. A–C show time courses for the solubilization of GlcNAc, and D–F show corresponding time courses for the solubilization of oxidized products. The legends shown in A–C also apply to the respective panels shown below (D–F). In the reactions shown in A, B, D, and E, AscA was added at 0 h, whereas C and F show reactions with AscA supplementation at either 0 or 6 h. Before analysis, soluble products generated by Jd1381 were converted to GlcNAc and chitobionic acid by overnight incubation with 1.5 μm SmCHB (chitobiase, an N-acetylhexosaminidase) at 37 °C (60). The data points represent the means of three independent experiments ± S.D. Incubation of these chitin substrates under the same conditions but in the absence of enzyme did not yield detectable levels of soluble products.