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Protein A Ligands


Leader in Protein A ligand manufacturing since 1985.
Most of the world's commercial monoclonal antibodies are purified using native and recombinant Protein A ligands manufactured by Repligen.

Leader in Protein A Ligand Manufacturing

Protein A is a critical component of proprietary products that are used every day in biopharmaceutical purification processes supporting the safe and effective production of important breakthrough drugs for diseases such as rheumatoid arthritis, breast cancer and multiple sclerosis.

Since 1985, Repligen Protein A ligands have been used in small- to large-scale purification and immunoprecipitation, or by OEM partners who use them as critical raw materials in the manufacure of their own proprietary products.  

Recombinant Protein A is expressed in Escherichia coli (E. coli) as opposed to the native protein extracted from Staphylococcus aureus. Repligen leverages its expertise in the optimization of E. coli fermentation and purification processes to deliver Protein A ligands that enable very high expression levels and yield in downstream purification.

Repligen supplies Protein A ligands in milligram to multi-kilogram quantities.  

Repligen develops and manufactures products for the biopharmaceutical industry under an ISO 9001 quality management system.  We focus on the timely delivery of high quality, consistent and robust products, to ensure business continuity for our customers.

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NGL-IMPACT® A Protein a Ligand

NGL-Impact® A ligand is a paradigm-changing solution that can deliver higher performance, lower cost Protein A resin for capture chromatography.

Co-developed over 2 years with Navigo Proteins, NGL-Impact® A Ligand was developed through a series of steps, including wild type Protein A shuffling, screening and multimerization.  The result is a market-leading ligand that responds to the need for capture resins with better binding capacity, caustic stability and elution while reducing costs and improving process economics.



Protein A Ligands

rSPA –Native Recombinant Staphylococcal Protein A Ligand – is the most advanced non-mutant Protein A ligand available from Repligen. The combination of performance and purity to native Protein A and outstanding economics and supply chain security, makes rSPA the automatic first choice for all new Protein A ligand applications.

  • Contains the same amino acid sequence and molecular mass as the native Protein A sourced from S. aureus
  • Manufactured with animal-free materials
Protein A Ligands


srPA50 Ligand

srPA50 ligands are produced in Escherichia coli. This ligand is identical to Repligen's original recombinant construct. It is an exact sequence match to rPA50 having all five IgG binding domains (E, D, A, B, C). The notation "s" in front of the rPA50, identifies that the protein srPA50 is manufactured with soy based, animal free fermentation media.

rPA50 Ligand

Discontinued by formal notification of obsolescence , June 23, 2016. 

Please substitute all future orders for rPA50 with the equivalent product srPA50.

Protein A Ligands

Native Protein A ligand

Protein A Ligands

Native Protein A is a purification ligand used to isolate IgG from crude protein mixtures.  It binds with high affinity to the Fc region of IgG's. When immobilized on a matrix, e.g; Sepharose, Protein A (native) can be used to isolate IgG from crude protein mixtures.

Native Protein A meets the strictest demands of drug manufacturers in terms of purity, reproducibility, binding capacity, specificity and other key measures critical to the quality of downstream processes.

  • Reliable performance: Fc specific binding to IgG
  • Guaranteed purity: > 95% purity by SEC
  • Activity: > 95% IgG-binding activity
  • Not purified by hIgG affinity
  • Produced according to cGMP