Glycosylation patterns

T. A. Gerken, C. L. Owens, and M. Pasumarthy, Determination of the site-specific O-glycosylation pattern of the porcine submaxillary mucin tandem repeat glycopeptide, J. Biol. Chem., 272 (1997) 9709-9719. 

Although capable of glycosylating heterologous human proteins, the glycosylation pattern usually varies from the pattern observed on the native glycoprotein (when isolated from its natural source, or when expressed in recombinant animal cell culture systems). 

Post-translational modifications, in particular glycosylation patterns, can be incomplete and/or can differ very significantly from patterns associated with native human glycoproteins. 

Incomplete (N-linked) glycosylation prompts decreased in vivo activity due to more rapid hepatic clearance of the EPO molecule. Enzymatic removal of terminal sialic acid sugar residues from oligosaccharides exposes otherwise hidden galactose residues. These residues are then free to bind specific hepatic lectins, which promote EPO removal from the plasma. The reported plasma tm value for native EPO is 4-6 h. The tm for desialated EPO is 2 min. Comparison of native human EPO with its recombinant form produced in CHO cells reveals very similar glycosylation patterns. 

A recombinant form of factor Vila (called NovoSeven or eptacog alfa-activated ) is marketed by Novo-Nordisk (Table 12.2). The recombinant molecule is produced in a BHK cell line, and the final product differs only slightly (in its glycosylation pattern only) from the native molecule. 

Scheme 1.—AFlow Chart Outlining the Methodologies for Profiling Protein Glycosylation Patterns.

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