Unusual role of the 2-OH group of oligosaccharide substrates in the mechanism of Bacillus 1,3-1,4-β-glucanase

Antoni Planas, Juan Nieto, Mireia Abel, Antoni Segade

Research output: Indexed journal article Articlepeer-review

2 Citations (Scopus)


In the mechanism of retaining β-glycosidases, the 2-hydroxyl group of the substrate in the monosaccharyl unit involved in catalysis (subsite - 1) is believed to play an important role through hydrogen bonding interactions with protein residues that are optimized at the transition state. Commonly, removal of the 2-OH group of the substrate results in a 10-12 kcal.mol-1 transition state destabilization. However, this effect seems not to be general as reported here for Bacillus 1,3-1,4-β-glucanase, a family 16 retaining endo-glycosidase. A p-nitrophenyl 2-deoxy tetrasaccharide substrate was synthesized to probe the involvement of the 2-OH group in catalysis. Comparative kinetics with wild-type and subsite +1 mutants show that the 2-deoxy analog is a better substrate than the corresponding 2-hydroxy substrate. It is tentatively proposed that the 2-deoxy analog adopts a different conformation upon binding that compensates for the lack of the 2-OH substituent.

Original languageEnglish
Pages (from-to)223-231
Number of pages9
JournalBiocatalysis and Biotransformation
Issue number4-5
Publication statusPublished - Aug 2003
Event5th Carbohydrate Bioengineering Meeting - GRONINGEN, Netherlands
Duration: 6 Apr 20039 Apr 2003


  • 2-deoxyglycoside
  • Glycosidase
  • Mechanism
  • Non-covalent interactions
  • Ring distortion


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