Sodium dodecyl sulphate-treated proteins as ligands in ELISA

Insoluble proteins generally do not adsorb to microtitre wells and, therefore, cannot be used as antigens in enzyme-linked immunosorbent assay (ELISA). However, denaturation and solubilization with 2% sodium dodecyl sulphate (SDS) renders these proteins suitable ligands for ELISA. In quantitative ELISA using polyclonal antibodies as primary antibody, comparable results were obtained with native and SDS-denatured protein ligands. The binding of the antibodies to the SDS-treated ligands was completely inhibited by premixing the primary antibody with the corresponding native antigen. Nonspecific binding of primary and secondary antibodies to SDS-treated ligands was not observed. SDS-treated proteins are able to attach to ELISA microwells, retain their antigenic epitopes and do not engender an elevated background. The concentration of SDS-treated proteins required for coating is the same as that of the native proteins.