23:T550,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.24:T4af,The released milk N-glycome has been found to possess antipathogenic activity. Natively, they are covalently linked onto proteins. Whether the conjugated N-glycans still have antipathogenic properties and how the glycosylation influences the antipathogenic activity of proteins remain unclear. Herein, we compared the quantitative differences of milk protein N-glycosylation and the antilisterial differences of native milk proteins, released N-glycan pools, and deglycosylated proteins between human and bovine milk. N-glycosylation exhibited to be quantitatively species-specific. The entire growth inhibitory activity and the majority of the antiadhesive activity against Listeria monocytogenes of milk whey proteins, although not as high as the released N-glycans, are attributed to N-glycosylation. Moreover, all N-glycan-bearing samples from human milk showed better growth inhibitory activities than those from bovine milk. Generally, N-glycosylation significantly contributes to the antilisterial function of milk proteins and to the functional differences between species. This gives novel insights into the role of these glycoconjugates in nature.

#	Concept	H-Index	Publications	Citations
1	Engineering	2	2	56
2	Medicine	1	1	35
3	Biochemistry	1	1	35
4	Chemical Engineering	1	1	21
5	Chemistry	1	1	21

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