초록
<P>This is the first report describing the cloning, expression, and characterization of a putative thermostable, cellulase-free xylanase (XYN) from the thermophilic bacterium Thermoanaerobacterium thermosaccharolyticum DSM 571. The temperature and pH values for optimal enzyme activity of XYN were found to be 65 C and pH 6.5, respectively. The XYN activity was apparently enhanced by Co(2+), Mn(2+), and Tween 60 and significantly inactivated by Al(3+), Cu(2+), Zn(2+), and SDS. The K m and V max values of XYN for the hydrolysis of beechwood xylan were 2.1 mg/ml and 222.1 U/mg, respectively. The k cat values of XYN for beechwood xylan at the optimal temperature and pH values were 481.4 s(-1). XYN represents an attractive candidate for use in the large-scale production of xylooligosaccharides (XOs) from forest residues because it is an endo-xylanase capable of degrading xylan.</P>