Development of novel methodology for rapid conjugated oligosaccharide synthesis

Abstract

Glycosylation is one of the most important post-translation modifications of proteins, which affects biological activities by way of controlling higher order structure. Recently, the novel structure of glycoprotein, namely C-glycosyl protein was identified in various proteins. The first total synthesis of the naturally occurring C-glycosyl amino acid and peptide was achieved. The mannose and tryptophan moiety was connected via ring opening reaction of epoxide by lithiated indole derivative. After functional group conversion and deprotection, the glyco-amino acid was synthesized in a concise and stereoselective manner. To develop the rapid oligosaccharide construction methodology, the soluble polymer supported oligosaccharide was investigated. Due to high polarity of polymer support, the purification of PEG bound compound is achieved quite easily. The real-time monitoring of the glycosylation reaction was performed by MALDI-TOF MS, whereas the deprotection reaction of chloroacetyl group was performed by color test using (p-nitrobenzyl) pyridine. The purification of PEG bound compound which has chloroacetyl group, is achieved by capture-release strategy by use of resin bound cysteine derivative. By combination of these methodologies and novel linker, tetrasaccharides were synthesized.