ABSTRACT
Protein samples are separated by one-dimensional sodium dodecyl sulfate - polyacrylamide gel electrophoresis or two-dimensional gel electrophoresis in polyacrylamide gels. The separated proteins are then transferred to a nitrocellulose or nylon sheet. This is incubated with specific antibody to the protein and then unbound antibody is washed away. Immunoaffinity chromatography can be used to purify protein antigens by immobilizing the relevant antibodies on an inert matrix such as polysaccharide beads. When exposed to a protein mixture, only the protein recognized by that antibody will bind to the beads and can be eluted later in pure or almost pure form. Cells bearing the antigen on their surface can also be purified using a similar procedure. Because of the high specificity of an antibody for its epitope, an antibody raised against a particular protein antigen can be used to determine the location of that antigen in a cell using immunofluorescence light microscopy or immuno-electron microscopy.
