title: Streptococcus pneumoniae endohexosaminidase D; feasibility of using N-glycan oxazoline donors for synthetic glycosylation of a GlcNAc-asparagine acceptor.
abstract: Endohexosaminidase D, a family 85 glycoside hydrolase from S. pneumoniae and the first endohexosaminidase to be discovered, is found to be capable of catalysing the glycosylation of a glycosyl amino acid bearing a GlcNAc residue using a variety of N-glycan oxazoline donors. Although enzyme-catalysed oxazoline hydrolysis is a significant competing reaction that is not countered by the addition of organic co-solvents or variation of reaction pH, a high yielding synthetic process can be achieved by the sequential addition of multiple equivalents of oxazoline donor, demonstrating the synthetic potential of this enzyme as a biocatalyst for the synthesis of defined glycoconjugates. Notably Endo-D does not appear to hydrolyse the resulting products under the conditions used. The synthetic activity displayed by Endo D implies that other, as yet untested, family GH85 enzymes may display similar synthetic potential. Furthermore since Endo D is capable of cleaving N-glycans attached to monoclonal antibodies (mAbs), and also of cleaving glycans that are core-fucosylated, the development of Endo D as a useful biocatalyst for the synthesis of important defined homogeneous complex glycoconjugates may have significant future potential, provided that the limitation of direct oxazoline hydrolysis can be surmounted.
authors.affiliation: Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, UKOX1 3TA.
authors.forename: Thomas B
authors.initials: TB
authors.lastname: Parsons
authors.forename: Mitul K
authors.initials: MK
authors.lastname: Patel
authors.forename: Alisdair B
authors.initials: AB
authors.lastname: Boraston
authors.forename: David J
authors.initials: DJ
authors.lastname: Vocadlo
authors.forename: Antony J
authors.initials: AJ
authors.lastname: Fairbanks
mesh_terms: D000117:Acetylglucosamine / Q000737:chemistry / Q000378:metabolism*; D001216:Asparagine / Q000737:chemistry / Q000378:metabolism; D002240:Carbohydrate Sequence; D006031:Glycosylation; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase / Q000378:metabolism*; D008969:Molecular Sequence Data; D010080:Oxazoles / Q000737:chemistry / Q000378:metabolism*; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism*; D013296:Streptococcus pneumoniae / Q000201:enzymology*
chemical_list: D010080:Oxazoles; D011134:Polysaccharides; D001216:Asparagine; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D000117:Acetylglucosamine