FIGURE 8.

Furin time course digestion of ANGPTL3 glycopeptides monitored by MALDI-TOF analysis. An ANGPTL3 17-mer peptide was glycosylated at Thr²²⁶ with GalNAc (Tn) by GalNAc-T2 and further extended to core 1 (T, Galβ1-3GalNAcα1-O-Ser/Thr) or STn (NeuAcα2-3GalNAcα1-O-Ser/Thr). The furin cleavage reactions were sampled after 0.5, 1.5, and 5 h. The non-glycosylated ANGPTL3 peptide was cleaved in the RAPR↓ motif to completion after 5 h, giving rise to peaks with the expected masses of the C-terminal (933 Da) and N-terminal peptides (1,011 Da). The glycopeptides (Tn, T, and STn ANGPTL3) were almost completely protected against proteolytic cleavage. Only trace amounts of the cleaved C- and N-terminal peptides were visible after 5 h of incubation.