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Publication Abstract from PubMed

In this paper, we characterized Am2136 as a beta-N-acetylhexosaminidase from Akkermansia muciniphila to perform the biochemical characteristics and the crystal structure of selenomethionine-labeled Am2136 with GlcNAc complex. Crystallographic evidence suggests that an oxazolinium ion was formed intermediately by the 2-acetamido group during the substrate-assisted catalytic procedure. Structural and kinetic analysis of native Am2136 and D412A, E413A mutants were investigated and the results revealed substantial difference. The Kcat/Km value of D412A was decreased 4297-fold compared to native Am2136 revealed that mutation of Asp-412 results in preventing the 2-acetamido substituent from providing anchimeric assistance and thus reducing the catalytic efficiency. Moreover, Am2136 has a wide dependence on pH and temperature, while sensitive to divalent metal ions such as Ca(2+) and Mn(2+). These biochemical and crystallographic results provide evidences that Asp-412 residue assists to orient the 2-acetamido group for catalysis. Based on crystallographic evidence and sequence alignment with other GH family 20 enzymes, Asp-412 residue is possibly fundamental for Am2136 during substrate-assisted catalysis.

Biochemical characteristics and crystallographic evidence for substrate-assisted catalysis of a beta-N-acetylhexosaminidase in Akkermansia muciniphila.,Chen X, Li M, Wang Y, Tang R, Zhang M Biochem Biophys Res Commun. 2019 Sep 10;517(1):29-35. doi:, 10.1016/j.bbrc.2019.06.150. Epub 2019 Jul 23. PMID:31345574^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.