SMALL-SCALE SOLID-PHASE O-GLYCOPEPTIDE SYNTHESIS OF LINEAR AND CYCLIZED HEXAPEPTIDES FROM BLOOD-CLOTTING FACTOR-IX CONTAINING O-(ALPHA-D-XYL-1-]3-ALPHA-D-XYL-1-]3-BETA-D-GLC)-L-SER

Glycopeptide sequences corresponding to residues 51-56 of the EGF-like domains of human and bovine blood-clotting factor IX have been synthesized using the Fmoc/Dhbt strategy. Building blocks consisting of Fmoc-Ser(R)-OPfp, where R = beta-D-Glc or alpha-D-Xyl-(1-3)-alpha-D-Xyl-(1-3)-beta-D-Glc, have been synthesized. The building blocks were prepared by treatment of the unprotected glycosylated serine compounds with N-(fluoren-9-ylmethoxycarbonyl)succinimide in 1,4-dioxane, followed by treatment with pentafluorophenol and dicyclohexylcarbodiimide in tetrahydrofuran. The glycosylated building blocks were then used in a solid-phase peptide synthesis to give the corresponding glycopeptides. Cyclic glycopeptides were prepared from the acetamidomethyl-protected linear glycopeptides by treatment with thallium(III) trifluoroacetate in trifluoroacetic acid. The cyclic glycopeptides were fully characterized by NMR spectroscopy and mass spectrometry.