@article{hronská_štefuca_ondrejková_bláhová_višňovský_rosenberg_2022, 
  title={Chemo-Enzymatic Production of 4-Nitrophenyl-2-acetamido-2-deoxy-α-D-galactopyranoside Using Immobilized β-<i>N</i>-Acetylhexosaminidase}, 
  volume={12}, 
  DOI={10.3390/catal12050474}, 
  abstractNote={α-Nitrophenyl derivatives of glycosides are convenient substrates used to detect and characterize α-<i>N</i>-acetylgalactosaminidase. A new procedure combining chemical and biocatalytic steps was developed to prepare 4-nitrophenyl-2-acetamido-2-deoxy-α-D-galactopyranoside (4NP-α-GalNAc). The α-anomer was prepared through chemical synthesis of an anomeric mixture followed by selective removal of the β-anomer using specific enzymatic hydrolysis. Fungal β-<i>N</i>-acetylhexosaminidase (Hex) from <i>Penicillium oxalicum</i> CCF 1959 served this purpose owing to its high chemo-and regioselectivity towards the β-anomeric <i>N</i>-acetylgalactosamine (GalNAc) derivative. The kinetic measurements of the hydrolytic reaction showed that the enzyme was not inhibited by the substrate or reaction products. The immobilization of Hex in lens-shaped polyvinyl alcohol hydrogel capsules provided a biocatalyst with very good storage and operational stability. The immobilized Hex retained 97% of the initial activity after ten repeated uses and 90% of the initial activity after 18 months of storage at 4 °C. Immobilization inactivated 65% of the enzyme activity. However, the effectiveness factor and kinetic and mass transfer phenomena approached unity indicating negligible mass transfer limitations.}, 
  number={474}, 
  publisher={MDPI AG}, 
  author={Hronská and Štefuca and Ondrejková and Bláhová and Višňovský and Rosenberg}, 
  year={2022}
  }