Protein A Recombinant Rat mAb (S-2863)

Protein A is a 42 kDa cell-wall protein originally isolated from the non-pathogenic bacterium Staphylococcus aureus. Its defining feature is a string of five highly homologous immunoglobulin-binding domains that bind the Fc region of most mammalian IgG molecules with nanomolar affinity while leaving antigen-binding sites free. This exquisite specificity underpins its central role in biotechnology: Protein A is covalently immobilized on chromatography resins to create the gold-standard affinity medium for capturing monoclonal and polyclonal antibodies during downstream processing, enabling >99 % purity in a single step. Engineered variants, such as alkaline-tolerant or protease-resistant “Z-domain” forms, have further expanded its utility in large-scale biomanufacturing. Beyond purification, soluble Protein A conjugates and fusion proteins are employed in immunoprecipitation, biosensors, and targeted drug delivery, making it one of the most indispensable tools in modern life sciences.