In view of the important role of glycoconjugates in biological recognition, acute and chronic diseases (such as inflammation), and numerous cancer types; methods capable of introducing an unnatural sugar at a unique site in the oligosaccharide chain of relevant glycoprotein and/or glycolipid are highly desirable. We have developed mutant glycosyltransferases that are capable of transferring modified sugars to specific monosaccharide residue on a glycan chain. We are currently synthesizing novel unnatural carbohydrates that will contain the functionality for incorporating probes and/or biomarkers. We plan to exploit this technology for the analysis of �under-� and �over-glycosylated� glycans related to certain disease. These techniques will facilitate the tracing of aberrant glycosylation patterns associated with diseases, as well as the analysis or diagnosis of specific glycoconjugates related to biological recognition, and drug therapy. In addition, this method may have vast biological applications, such as the development of targeted drug delivery systems, fluorescent derivitization for glycomic analysis, or contrast agents for MRI.