Discovery of β--acetylglucosaminidases from screening metagenomic libraries and their use as thioglycoligase mutants.

β--Acetylhexosaminidases (HexNAcases) are versatile biocatalysts that cleave terminal -acetylhexosamine units from various glycoconjugates. Established strategies to generate glycoside-forming versions of the wild type enzymes rely on the mutation of their catalytic residues; however, successful examples of synthetically useful HexNAcase mutants are scarce. In order to expand the range of HexNAcases available as targets for enzyme engineering, we functionally screened a metagenomic library derived from a human gut microbiome.