Beta-N-Acetylhexosaminidases accept 4-deoxy-N-acetylhexosaminides as substrates

b-N-Acetylhexosaminidases (EC 3.2.1.52, CAZy GH20) possess so called wobbling specificity, which means that they cleave substrates both in gluco- and galacto- configurations, with the activity ratio depending on the enzyme source. Here we present a new finding that fungal b-N-acetylhexosaminidases are also able to hydrolyze and transfer 4-deoxy-N-acetylhexosaminides. This fact clearly demonstrates that the 4-hydroxy moiety at the substrate pyranose is not essential for the binding of the substrate to the enzyme's active site, which was also confirmed by molecular docking of the tested compounds into the model of the active site of b-N-acetylhexosaminidase from Aspergillus oryzae. A set of four 4-deoxy-N-acetylhexosaminides was prepared via chemical synthesis and screened against a panel of b-N-acetylhexosaminidases from various types of sources (fungal, human, animal, plant and bacterial representatives) for hydrolysis. The results of this screening as well as structures of 4-deoxy disaccharides prepared by transglycosylation reaction using b-N-acetylhexosaminidase fromTalaromyces flavus are reported. This structure-function relationship study will be used in the design of new b-N-acetylhexosaminidase inhibitors and for the synthesis of novel type of glycomimetics.