Fetuin analysis

The strategy used to perform the PMP oligosaccharide profile analysis, with the use of bovine fetuin as a model system, is given in Scheme 1. Bovine fetuin, a major glycoprotein in fetal calf serum, has been widely used as a model for the study of glycoprotein structure. This glycoprotein contains both N- and O-linked oligosaccharides and detailed structural information is available (9-11). 

With bovine fetuin as a model system, the use of PMP labeling in the routine rp-HPLC profile analysis of glycoproteins has been evaluated. Comparable profiles for oligosaccharides can be obtained regardless of whether they are released by automated chemical or manual enzymatic treatments. The PMP-oligosaccharide samples recovered fi om HPLC are suitable for MALDI TOP and LC ESI mass spectrometric analysis. The presence of all three N-linked and one of the 0-linked oligosaccharides was confirmed. 

The 0-glycosically linked carbohydrate chains of fetuin have been cleaved from the protein by alkaline borohydride treatment. Structural analysis revealed the existence of tri- and tetra-saccharides linked 0-glycosidically to L-serine or L-threonine and having structures identical to those previously identified for bovine K-casein and human chorionic gonadotrophin [(27) and (28)]. The A-glycosidically linked chains of fetuin have been assigned structures (36) %r (37). ... 

FIGURE 4 HPLC chromatograms of the peptides produced from bovine fetuin by trypsin and Asp-N as measured by the electrospray mass spectrometer (A) Total ion current (TIC) (B) reconstructed ion chromatogram (RIC) for ion 204. Glycopeptides containing residues Asn 81, Asn 138, Asn 158, Ser 253, and Thr 262/Ser 264 were observed in the LC/MS analysis. Reprinted, with permission, from Carr et al. (1993). 

The profiles for the analysis of the neutral and acidic monosaccharides released from bovine fetuin are shown in Figures 8.9 and 8.10. The quantitative results (Table 8.1) are in line with published data for a multicenter study [18]. 

Hydrazinolysis, deamination, and methylation analysis have demonstrated that ai-acid glycoprotein, fetuin, lactotransferrin, and transferrin possess structural features in common. ... 

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