A synthetic glycoconjugate (neoglycoprotein) of BSA where N-Acetyl-D-glucosamine (GlcNAc) has been conjugated to BSA at multiple lysines by highly stable amide linkages via a discrete 9-atom triethylene glycol (PEG3) linker/spacer system functionalized with carboxylic acid. O-GlcNAc regulates protein functions at multiple levels, including enzymatic activity, transcriptional activity, subcellular localization, intermolecular interactions and degradation. Abnormal O-GlcNAcylation is associated with many human diseases including cancer, diabetes and neurodegenerative diseases.