Studies of post-translational modification by β-N-acetyl-D-glucosamine (O-GlcNAc) are hampered by a lack of efficient tools such as O-GlcNAc specific antibodies that can be employed for detection, isolation, and site localization. We have obtained a large panel of O-GlcNAcspecific IgG MAbs having a broad spectrum of binding partners by combining three-component immunogen methodology with hybridoma technology. Immunoprecipitation followed by largescale shotgun proteomics led to the identification of more than 200 mammalian O-GlcNAc modified proteins, including a large number of novel glycoproteins. A substantial number of the glycoproteins were only enriched by one of the antibodies and this observation combined with results of inhibition ELISAs suggests that the antibodies in addition to their O-GlcNAcdependence also appear to have different, but overlapping, local peptide determinants. The MAbs made it possible to delineate differentially modified proteins of liver in response to traumahemorrhage and resuscitation in a rat model.

A novel approach for the synthesis of various fragments of proteophosphoglycans from Leishmania major and Leishmania mexicana proteophosphoglycans has been developed. These compounds have been obtained by coupling alpha-mannosyl and alpha-N-acetyl-glucosamine phosphoramidite derivatives with the serine hydroxyl of various amino acids and peptides to give, after oxidation with tert-BuOOH, phosphotriesters exclusively as alpha-anomers in good yield. The resulting compounds could be deblocked using conventional methods. Glycophosphorylation of preassembled and properly protected peptides was found to be more efficient for the preparation of proteophosphoglycan fragments than a building block approach strategy using a phosphoglycosylserine derivative.

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