Other Names

SPA

Background

Staphylococcus Aureus Protein A (SPA or Protein A) is a 42kDa surface protein named MSCRAMM(Microbial Surface Components Recognizing Adhesive Matrix Molecules), it is originally found in the cell wall of the bacteria Staphylococcus aureus. It is composed of five homologous Ig-binding domains that fold into a three-helix bundle. Each domain is able to bind proteins from many mammalian species, most notably IgGs. Protein A can bind with strong affinity to human IgG1, human IgG2, mouse IgG2a and IgG2b, and with medium affinity to human IgM, IgA and IgE as well as mouse IgG3 and IgG1. Protein A can not bind to human IgG3,IgD or react with human IgM, IgA, IgE..

Protein A is widely used in biomedicine field because of its strong affinity to immunoglobulins. Protein A used to produce antibodies in the medicine field are mostly the ones binding to stationary-phase Chromatographic Resin.

A small amount of protein A used in affinity chromatography may fall off the chromatographic column, and enter into elution tank. Leakage of protein A  may contaminate the antibodies during the production process. Protein A has the ability to interactwith multiple hosts, which indicate it might be a virulence factor in Staphylococcus aureus infection. To ensure the quality of antibodies purified by Protein A affinity chromatography, we have successfully developed Protein A ELISA kit. The kit is also applicable for the quantitative measurement of protein A in the samples with highly concentrated antibody such as purified antibody end products.