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