Protein A is a membrane protein of Staphylococcus aureus and can specifically bind to antibodies. Protein A affinity chromatography columns have become widely used as affinity columns for purified antibodies from ascites, serum and cell culture isolated or purified extracts of antibodies from different subtypes of mammals or genetically engineered recombinant proteins containing antibody Fc fragments. alkali protein A is our company independent research and development production, with independent intellectual property rights. Recombinant protein A is expressed by E. coli and purified by chromatography to give a purity of 95% or more. The purification process does not use antibody column affinity chromatography to avoid the possibility of incorporation of unrelated IgG in the product.