ProteinSimple eBook - 14

Simplifying Protein Analysis * Mastering Charge Heterogeneity Analysis of Therapeutic Proteins

with icIEF methods to ensure consistent results (Figure 4B). Using improperly
stored or expired consumables and reagents can also have a profound effect
on performance. This is especially true for methods that employ urea to
eliminate aggregation. Urea solutions should be made fresh and kept away
from heat to avoid thermal degradation. One of the thermal degradation
products of urea, isocyanic acid, will rapidly react with amine groups and
artiﬁcially increase a protein's acidic species' percent composition (Figure 4A).

Conclusion
The iCE3 system's quick and easy icIEF method development lets even
those analysts new to icIEF develop robust charge heterogeneity methods in
an afternoon by following some simple procedures and guidelines. Potential
issues that can arise with commonly interfering sample matrix components
are easily resolved through addition of solubilizers, dilution, or buffer exchange.
In addition, the high-resolution, 10-minute separations obtained are ideal for
the characterization and monitoring of charge variants in biopharmaceutical
formulations. n

Scott Mack, Ph.D., Senior Scientist and
Alpana Prasad, Ph.D., Product Manager
ProteinSimple
14

| GENengnews.com

Figure 4. High-quality reagents help ensure consistent results.
(B) For example, if urea solutions are used, they should be made
fresh and kept away from heat. Doing so can avoid artificial
increases in a protein's acidic species' percent composition (A).

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