Enzymic methods glycosylations with transferases,

Alternative methods of highly selective coupHng reactions were developed using enzymes. These methods were easier to develop on a large number of proteins with little effort. In the first example, the PEG chain can be transferred on an O-glycosylated site of glycosylated native proteins. The reaction can be catalysed by a specific enzyme, a glycosyl transferase, which confers a... 

Recently, a universal enzyme-coupled fluorescence assay for glycosyl transferases was developed. This method is extremely cost-effective and is based on the quantification of nucleotides produced in the glycosyl transfer reaction. The guanosine diphosphate (GDP), uridine diphosphate (UDP), and cytidine monophosphate (CMP) are phos-phorylated with nucleotide kinase in the presence of excess of ATP, generating ADP. Via coupled enzyme reactions involving ADP-hexokinase,glucose-6-phosphate dehydrogenase, and diaphorase, the ADP is utilized for the conversion of resazurin to resorufin, which is then quantified by fluorescence measurement. 

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