Highly sensitive quantification with Enzo’s Protein A ELISA

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Role of Protein A in Antibody Purification

Protein A is a 42kDa protein anchored in the cell wall of S. aureus. It has the ability to selectively interact with the Fc region of IgG. This selectivity is used to purify IgG and remove over 98% of impurities from complex solutions such as cell harvest media in a single column-based purification step. However, leached protein A in solution or bound to the Fc region of the purified IgG may remain after this process. The presence of such a contaminant in purified antibodies must be avoided, especially if these were manufactured for clinical use as it could lead to severe adverse effects in patients. There is therefore a need for robust tools for the detection of protein A in bioprocess samples.

Although techniques such as surface plasmon resonance (SPR) can be used, they often lack sensitivity. Immunoassays provide a high-throughput, sensitive, and well-validated alternative solution.

Advantages of Enzo’s Protein A ELISA Kit

Thanks to its high-throughput format, Enzo’s Protein A ELISA kit delivers results in less than three hours for up to 37 samples in duplicate. The antibody included in the kit recognizes several protein A constructs commonly used by the biopharmaceutical industry with recovery at or near 100%, making it a single, adaptable, and flexible solution for users of multiple protein A variants (Fig. 1). It detects as little as 9.01 pg/ml (<1 ppm) of protein A residuals in purified monoclonal antibody preparations with high sensitivity and was shown to be more sensitive than the competition with most protein A cross-reactants including Cytiva’s MabSelect SuRe™ (Fig. 2).

Consistent Performance and Reliability

Finally, it displays negligible lot-to-lot variability with near perfect overlay of the standard curves of 12 lots over a period of 12 years indicating this is a reliable solution end users can trust day-in, day-out (Fig. 3). Overall, this value proposition makes Enzo’s Protein A ELISA kit the industry’s reference when it comes to the quantification of protein A contaminants in purified monoclonal antibody preparations in bioprocess.