eBook: Product-Related Impurities — From Identification to Prevention of Product Variance

Product variants differ from desired biological proteins in their structure, activity, efficacy, and even safety. Unlike process-related impurities — which must be monitored, controlled, and cleared during downstream processing — product variants can be managed partly through preventive measures. Authors in this eBook highlight recent advances in technologies for detection and identification, trends in formulation that complicate the product-variant issue, and chemical and genetic means of preventing changes to protein structure during processing. First, BPI’s editor in chief introduces these themes with a brief review of recent papers published in the scientific journal mAbs. Then, authors from AGC Biologics present a new example approach in “Maintaining Protein Disulfide-Bond Stability During Culture Harvest: Exploring the Effects of Temperature and Oxygen on Reduction-Reaction Kinetics.” They investigate the kinetics of thioredoxin reductase (TrxR) enzymatic activity, focusing on the effects of reactive oxygen species and oxygen inhibition. After providing calculations for optimal DO levels for minimized TrxR-mediated protein reduction, the authors explore the role of harvest temperature as a mitigative factor in reducing disulfide-bond reduction rates. This should aid other developers seeking to optimize harvest processes to enhance protein quality.

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