Xyn10A, a thermostable endoxylanase from Acidothermus cellulolyticus 11B.

We cloned and purified the major family 10 xylanase (Xyn10A) from Acidothermus cellulolyticus 11B. Xyn10A was active on oat spelt and birchwood xylans between 60°C and 100°C and between pH 4 and pH 8. The optimal activity was at 90°C and pH 6; specific activity and K(m) for oat spelt xylan were 350 μmol xylose produced min⁻¹ mg of protein⁻¹ and 0.53 mg ml⁻¹, respectively. Based on xylan cleavage patterns, Xyn10A is an endoxylanase, and its half-life at 90°C was approximately 1.5 h in the presence of xylan.