Figure 7
Key catalytic residues analysis of Xyn10A and Xyn10B through site-directed mutagenesis.
The residues are Glu493, Glu601 and Trp658 for Xyn10A and Glu139, Glu247 and Trp305 for Xyn10B. (A) Three-dimensional homology modeling of Xyn10A. (B) Three-dimensional homology modeling of Xyn10B. The three-dimensional homology models of Xyn10A and Xyn10B were constructed by the ModWeb server. The crucial residues Glu493, Glu601 and Trp658 for Xyn10A and Glu139, Glu247 and Trp305 for Xyn10B were marked by black arrows. (C) SDS-PAGE of the purified mutations. (D) Hydrolytic properties of the purified mutations on XOS. The reaction mixtures contained 25 μg/ml enzyme (Xyn10A-TM2, Xyn10B and their mutations) and 10 mg/ml XOS at 55 °C in citrate buffer (pH 6.0, 50 mM sodium citrate, 150 mM NaCl) for 6 h, the productions were analyzed by TLC. X1, xylose; X2, xylobiose; X3, xylotriose; X4, xylotetraose.
