Protein A is a cell-wall surface protein originally found in Staphylococcus aureus with a molecular weight of approximately 42 kDa It specifically binds to the Fc region of mammalian immunoglobulins (Ig) and also interacts with the Fab region of human VH3 family antibodies This product is an engineered recombinant Protein A fragment (25 kDa) covalently coupled to nanoscale magnetic beads The modified Protein A retains only the amino acid sequences responsible for Fc-region binding (e g IgG) removing sequences associated with potential non-specific interactions thereby minimizing non-specific bindings efficiently Protein A beads selectively bind compatible antibodies including human IgG1 IgG2 IgG4 mouse IgG2a IgG2b and rabbit IgG among others Each Protein A molecule is capable of binding five IgG molecules These beads are primarily designed for IP CoIP ChIP assays and antibody purification from sera cell culture supernatants or ascites fluid samples