Synthesis of glycosylated peptides by NCA polymerization for recognition of human T-cells

Peracetylated sugars (glucose, mannose, galactose) were attached via a thiourea linker to the ε-amino group of α-BOC-lysine and α-Z-lysine. After transformation to the N-carboxyanhydride (NCA), the product was copolymerized with both PEGylated lysine-NCA and ε-TFA-lysine-NCA by both tertiary amine and nickel complex catalysts. The resulting statistical copolypeptides are water-soluble after global deprotection and show an α-helical secondary structure. Fluorescein isothiocyanate (FITC) was then coupled to the free ε-NH2 groups of the lysine repeating units. The galactosylated fluorescent peptides are specifically incorporated in human T lymphocytes at 37 °C, as shown by flow cytometry and fluorescence microscopy. Therefore they are potentially useful for selective staining of cells or targeted drug delivery.