UNIT 10.24 Solution Radioimmunoassay of Proteins and Peptides

  1. John A. Smith

Published Online: 1 MAY 2006

DOI: 10.1002/0471142727.mb1024s74

Current Protocols in Molecular Biology

Current Protocols in Molecular Biology

How to Cite

Smith, J. A. 2006. Solution Radioimmunoassay of Proteins and Peptides. Current Protocols in Molecular Biology. 74:VI:10.24:10.24.1–10.24.18.

Author Information

  1. University of Alabama at Birmingham, Birmingham, Alabama

Publication History

  1. Published Online: 1 MAY 2006
  2. Published Print: APR 2006


This unit describes a solution-phase radioimmunoassay (RIA) using the double antibody/PEG method. A solution RIA determines the amount of a specific protein (or peptide) in a sample by comparison to a standard curve of the same protein (or peptide). The amount of protein (or peptide) in the sample is determined based on its ability to compete with a radiolabeled tracer for binding to a specific antibody. A secondary antibody and PEG are used to precipitate the primary antibody-protein complexes. The amount of radioactivity in the complex is inversely proportional to the amount of protein in the sample. Under ideal conditions, an RIA is capable of measuring picograms of a protein (or peptide), but only if the tracer is labeled at a high specific activity. To this end, this unit also presents protocols for radioiodination of proteins and peptides using lactoperoxidase or the Bolton-Hunter reagent.


  • antibody;
  • anti-protein antiserum;
  • double-antibody method;
  • RIA;
  • peptides;
  • polyethylene glycol;
  • proteins;
  • radioimmunoassay