Protein A ELISA

Test Principle

Our ELISA kit is designed to detect SpA in IgG-containing solutions (e.g. monoclonal antibody preparations), in acid eluates from SpA columns, and in other liquid preparations. It is a sandwich ELISA based on microtitre strips coated with affinity-purified chicken anti-SpA IgG. SpA from the sample is bound to the microwell.

Bound SpA is detected using biotinylated chicken anti-SpA IgG. A streptavidin horseradish peroxidase conjugate detects the biotin conjugate.

A substrate that reacts with horseradish peroxidase is added. Color development is due to conversion of the substrate by the conjugate. A positive result is indicated as a color change. The color can be read visually or by using a microplate photometer at 450 nm.

Samples to be tested with this assay are often of acidic. In order for the test to work properly, such samples should first be neutralized. If a sample contain mammalian IgG, SpA will interact with IgG and, hence, be partly blocked. A falsely lowered signal may result. To avoid this problem samples containing IgG are treated to denature the immunoglobulins and expose the available SpA epitopes.