A quantitative Western Blot method for protein measurement

A radioimmunologic assay method for the quantitation of small amounts of protein in recombinant vaccines at the level of 20-150 ng is evaluated which uses the techniques of SDS-PAGE and electrophoretic protein transfer ("Western Blot'). Known amounts of the protein being determined are included on the same gel as the unknown. After protein blotting, the nitrocellulose membrane is treated with antibody specific for the protein being determined and subsequently with [125I] Protein A. An autoradiogram is produced which corresponds directly to the nitrocellulose blot. It can, therefore, serve as a template to locate the labeled protein which is excised from the blot and measured in a gamma counter. The technique is found especially useful for evaluating cell lysates of recombinant bacteria and yeast for the percentage of the recombinant protein in the total protein mixture.