Sialic Acid Analysis


A negatively charged monosaccharide, sialic acid is found as a terminal epitope on a variety of glycans.

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Glycosylated proteins make up a significant portion of licensed therapeutic biological pharmaceuticals, such as erythropoietin (EPO), monoclonal antibodies (MAb), and other hormones. A negatively charged monosaccharide, sialic acid is found as a terminal epitope on a variety of glycans. N-acetylneuraminic acid (Neu5Ac) and N-glycolylneuraminic acid (Neu5Gc) are the two sialic acids that are most frequently found in biopharmaceuticals. Both human and non-human cells have Neu5Ac. With the exception of human cells, all mammalian cells generate neu5Gc. Neu5Gc is immunogenic in humans due to the single oxygen atom difference between it and its homolog Neu5Ac (Figure 1). Acetylation is a frequent alteration of therapeutic antibody sialic acid analysis. Clinical efficacy may be impacted by O-acetylation's ability to slow down the kinetics of enzyme-catalyzed glycan desialylation. The degree and kind of sialylation are regarded as critical quality attributes (CQA) because they influence the clinical manifestations of therapeutic glycoproteins (serum half-life, immunogenicity, activity, etc.). Consequently, it is required by regulation (ICHQ6B) to characterize sialylation at every stage of the product life cycle in order to track the following metrics:

Quantification of total silica: Neu5Ac and Neu5Gc (nanmol/mg protein)
The Neu5Gc concentration

O-acetylated sialic acid's presence

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