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Several peptides/small proteins and glycosylphosphatidylinositol (GPI) derivatives were prepared in order to compare them as substrates of sortase A (SrtA), a bacterial transpeptidase, for enzymatic coupling. The results suggested that the developed process could be used to synthesize several analogues of the human CD52 and CD24 antigens, which are naturally GPI-anchored glycopeptides/glycoproteins.

Several peptides/small proteins and glycosylphosphatidylinositol (GPI) derivatives were synthe- sized and compared as substrates of sortase A (SrtA), a bacterial transpeptidase, for enzymatic coupling. It was observed that peptides containing the LPKTGGS and LPKTGGRS sequences as sorting signals at the peptide C-terminus were effectively coupled to GPI derivatives having one or two glycine residues attached to the phosphoethanolamine group at the nonreducing end. This reaction was employed to prepare several analogues of the human CD52 and CD24 antigens, which are naturally GPI-anchored glycopeptides/glycoproteins. It was further observed that the trisaccharide GPI analogues 5 and 6 were better SrtA substrates than monosaccharide GPI analogue 4, suggesting that steric hindrance of the GPI analogues does not affect their peptidation reaction mediated by SrtA. Therefore, this synthetic strategy may be useful for the preparation of more complex GPI-anchored peptides, glycopeptides, proteins, and glycoproteins. [ABSTRACT FROM AUTHOR]