Glycoconjugate is the covalently bonded product of oligosaccharides to the biomolecules such as proteins and lipids.  They play indispensable role in the biological activities of mammalian cells from energy generation to cell signalling. These glycoconjugates with short oligosaccharide structures are important for the characterization and purification in the course glycoconjucate vaccine developements. Therefore, research in the engineering of the glycosyl precursors that create oligosaccharides with controlled size is important in carbohydrate synthesis.