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Open AccessArticle

Characterization of Stackebrandtia nassauensis GH 20 Beta-Hexosaminidase, a Versatile Biocatalyst for Chitobiose Degradation

1
Glycomics and Glycan Bioengineering Research Center (GGBRC), College of Food Science and Technology, Nanjing Agricultural University, Nanjing 210095, China
2
Department of Chemistry, Simon Fraser University, Burnaby, BC V5A 1S6, Canada
3
College of Life Sciences, Nanjing Agricultural University, Nanjing 210095, China
*
Authors to whom correspondence should be addressed.
Int. J. Mol. Sci. 2019, 20(5), 1243; https://doi.org/10.3390/ijms20051243
Received: 7 January 2019 / Revised: 21 February 2019 / Accepted: 4 March 2019 / Published: 12 March 2019
(This article belongs to the Special Issue Industrial Enzymes: Structure, Function and Applications)
An unstudied β-N-acetylhexosaminidase (SnHex) from the soil bacterium Stackebrandtia nassauensis was successfully cloned and subsequently expressed as a soluble protein in Escherichia coli. Activity tests and the biochemical characterization of the purified protein revealed an optimum pH of 6.0 and a robust thermal stability at 50 °C within 24 h. The addition of urea (1 M) or sodium dodecyl sulfate (1% w/v) reduced the activity of the enzyme by 44% and 58%, respectively, whereas the addition of divalent metal ions had no effect on the enzymatic activity. PUGNAc (O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino-N-phenylcarbamate) strongly inhibited the enzyme in sub-micromolar concentrations. The β-N-acetylhexosaminidase was able to hydrolyze β1,2-linked, β1,3-linked, β1,4-linked, and β1,6-linked GlcNAc residues from the non-reducing end of various tested glycan standards, including bisecting GlcNAc from one of the tested hybrid-type N-glycan substrates. A mutational study revealed that the amino acids D306 and E307 bear the catalytically relevant side acid/base side chains. When coupled with a chitinase, the β-N-acetylhexosaminidase was able to generate GlcNAc directly from colloidal chitin, which showed the potential of this enzyme for biotechnological applications. View Full-Text
Keywords: β-N-acetylhexosaminidases; Glycan degradation; exochitinase; GH20 family; Stackebrandtia β-N-acetylhexosaminidases; Glycan degradation; exochitinase; GH20 family; Stackebrandtia
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Wang, M.; Zheng, F.; Wang, T.; Lyu, Y.-M.; Alteen, M.G.; Cai, Z.-P.; Cui, Z.-L.; Liu, L.; Voglmeir, J. Characterization of Stackebrandtia nassauensis GH 20 Beta-Hexosaminidase, a Versatile Biocatalyst for Chitobiose Degradation. Int. J. Mol. Sci. 2019, 20, 1243.

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