Glycosylation biopharmaceutical

Many polypeptides undergo covalent modification after (or sometimes during) their ribosomal assembly. The most commonly observed such PTMs are listed in Table 2.7. Such modifications generally influence either the biological activity or the structural stability of the polypeptide. The majority of therapeutic proteins bear some form of PTM. Although glycosylation represents the most common such modification, additional PTMs important in a biopharmaceutical context include carboxylation, hydroxylation, sulfation and amidation these PTMs are now considered further. 

Technical advances facilitating genetic manipulation of animal cells now allow routine production of therapeutic proteins in such systems. The major advantage of these systems is their ability to carry out post-translational modification of the protein product. As a result, many biopharmaceuticals that are naturally glycosylated are now produced in animal cell lines. CHO and BHK cells have become particularly popular in this regard. 

This technique is also utilized in the biopharmaceutical industry to determine product homogeneity. Homogeneity is best indicated by the appearance in the gel of a single protein band, exhibiting the predicted pi value. Interpretation of the meaning of multiple bands, however, is less straightforward, particularly if the protein is glycosylated (the bands can also be stained for... 

Table 7.4 The molecular mass of some polypeptide biopharmaceuticals. Many are glycosylated, thereby exhibiting a range of molecular masses due to differential glycosylation...

In the case of glycoprotein biopharmaceuticals, the consequence of the multiple glycosylated products is the need for strict control of the manufacturing process to maintain a reproducible spectrum of products with consistent therapeutic profile. That biopharmaceuticals often contain mixtures of related products can also be advantageous to the pharmaceutical industry in warding off generic competition, due to the challenge of... 

This chapter describes some of the most important and well-studied forms of post-translational modifications of proteins, which have been associated with the production of glycoproteins as biopharmaceuticals from mammalian cell culture systems. Most attention is given to glycosylation because of its general importance for the activity of all these... 

Another cytokine class used as a biopharmaceutical is interleukin (IL), which consists of at least 25 different subtypes (IL-1 to IL-25). Except for IL-1, most interleukins are glycosylated and have a molar mass in the range of 15-30 kDa. IL-2 is the most well studied interleukin, and its recombinant form is approved for the treatment of renal cell carcinoma. Since the absence of glycosylation does not affect its biological activity, rIL-2 is produced in genetically engineered E. coli. 

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