The enzyme, originally isolated from the bacterium Bacillus halodurans C-125, releases the xylose unit at the reducing end of oligosaccharides ending with the structure β-D-xylopyranosyl-(1→4)-β-D-xylopyranosyl-(1→4)-β-D-xylopyranose, leaving the new reducing end in the α configuration. It is specific for the β anomers of xylooligosaccharides whose degree of polymerization is equal to or greater than 3.
The penultimate residue must be β-D-xylopyranose, but replacing either of the flanking residues with glucose merely slows the rate greatly.
Honda, Y. and Kitaoka, M. A family 8 glycoside hydrolase from Bacillus halodurans C-125 (BH2105) is a reducing end xylose-releasing exo-oligoxylanase. J. Biol. Chem.279 (2004) 55097–55103. [PMID: 15491996]
Fushinobu, S., Hidaka, M., Honda, Y., Wakagi, T., Shoun, H. and Kitaoka, M. Structural basis for the specificity of the reducing end xylose-releasing exo-oligoxylanase from Bacillus halodurans C-125. J. Biol. Chem.280 (2005) 17180–17186. [PMID: 15718242]