(d) Detecting proteins using antibodies

• Immunoassay techniques are used to detect and identify specific proteins

• These techniques use stocks of antibodies with the same specificity, known as monoclonal antibodies

  • Knowledge of monoclonal antibody production is not required.

• An antibody specific to the protein antigen is linked to a chemical ‘label’

  • The ‘label’ is often a reporter enzyme producing a colour change, but chemiluminescence, fluorescence and other reporters can be used.

  • In some cases the assay uses a specific antigen to detect the presence of antibodies.

• Western blotting is a technique, used after SDS–PAGE electrophoresis

• The separated proteins from the gel are transferred (blotted) onto a solid medium

• The proteins can be identified using specific antibodies that have reporter enzymes attached