Solid-phase synthesis of CD52 glycopeptide and an efficient route to Asn-core pentasaccharide conjugate.

The intact peptide sequence (18) as well as its glycoform carrying an N-linked core pentasaccharide (1) of CD52 antigen were prepared by means of solid-phase synthesis employing Fmoc-amino acids and benzyl-protected oligosaccharide-asparagine conjugate (3) as building blocks. It was concluded that the pentasaccharide structure had little influence on further peptide elongation in solid-phase synthesis and the benzylated pentasaccharide moiety was sufficiently stable to the 95% TFA acidic conditions used to release glycopeptide from the supporting resin. The paper also describes an efficient route leading to asparagine-core pentasaccharide conjugate (3) which was prepared in seven steps for an overall yield of 23% from monosaccharide units 5, 6, 7 and 8.