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16 Pharmaceutical Technology ® Bio/Pharma Outsourcing Innovation eBook February 2024 PharmTech.com Dr_Microbe, Paulista - stock.adobe.com A ffinity ligands play an exciting role in the ev- er-growing sphere of downstream process- ing. In speaking with Pharmaceutical Tech- nology ® , Phillip Elliott, PhD, associate director of Process Development, BioCina; Jan Bekker, PhD, di- rector, Business Development, Commercial and Tech- nical Operations, BioCina; and Parviz Shamlou, PhD, senior vice-president of Science & Technology, Abzena illuminate the newest innovations with affinity ligands and provide a deeper understanding of the role affinity ligands play in the future of downstream processing. Breaking down affinity ligands PharmTech: What are affinity ligands and how do they contribute to the downstream purification process? Bekker (BioCina): Affinity ligands are molecules that can bind with high affinity to specific targets. Affinity ligands can be used for various purposes, such as detec- tion, purification, or modulation of biological activities. Affinity chromatography is a separation method based on the specific binding interaction between an immo- bilized affinity ligand and its binding partner. The most common example in the realm of bioprocessing is Pro- tein A, which has an extremely high affinity for some immunoglobulin molecules. Other examples include antibody/antigen, enzyme/substrate, and enzyme/in- hibitor interactions. The degree of purification achieved by affinity purification can be quite high depending on the specificity of the interaction. Consequently, it is gen- erally the first step in a purification strategy. Release of the protein from the ligand is generally achieved by altering parameters such as pH, and so- dium chloride concentration or by the addition of a competitor for ligand binding. Shamlou (Abzena): In nature, there is a vast array of biomolecule interactions where binding of one molecule to another through receptor–ligand interac- tions is critical for biological function. This concept is A Closer Look at Affinity Ligands Daria Husni is assistant editor to Pharmaceutical Technology®. A look at the newest innovations offers a deeper understanding of affinity ligands and their role in the future of downstream processing.