Endohexosaminidase-catalysed glycosylation with oxazoline donors: fine tuning of catalytic efficiency and reversibility.
A complete series of oxazoline di-, tri-, tetra-, and hexasaccharides, corresponding to the core sections of N-linked glycoprotein high mannose glycans, together with the corresponding oligosaccharides containing a central glucose unit, were synthesised and tested as glycosyl donors for glycosylation of a GlcNAcAsn glycosyl amino acid catalysed by the endohexosaminidases M (Endo M), A (Endo A) and H (Endo H). Whilst Endo H did not catalyse any glycosylation reactions, both Endo M and Endo A efficiently catalysed glycosylations that were not limited to donors containing the Manbeta(1-->4)GlcNAc linkage. Precise structure activity relationships and time course studies have revealed fine-tuning of the efficiency of the synthetic processes which correlated both with the enzyme used and the precise oxazoline structure. Efficient irreversible glycosylation was achievable with both Endo M and Endo A, further demonstrating the use of structurally modified oxazoline donors as transition state mimics in order to promote enzyme-catalysed synthesis, whilst precluding product hydrolysis; enzymes in these cases display "glycoligase" activity.
Rising
Thomas W D F
TW
Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford, UK.
Heidecke
Christoph D
CD
Moir
James W B
JW
Ling
Zhenlian
Z
Fairbanks
Antony J
AJ
D001173:Arthrobacter / Q000201:enzymology*; D002384:Catalysis; D006031:Glycosylation; D006596:Hexosaminidases / Q000737:chemistry* / Q000378:metabolism; D009089:Mucor / Q000201:enzymology*; D010080:Oxazoles / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D013329:Structure-Activity Relationship
D010080:Oxazoles; D006596:Hexosaminidases