Radioiodination of proteins

Many different substances can be labeled by radioiodination. Such labeled molecules are of major importance in a variety of investigations, e.g., studies of intermediary metabolism, determinations of agonist and antagonist binding to receptors, quantitative measurements of physiologically active molecules in tissues and biological fluids, and so on. In most of those studies, it is necessary to measure very low concentrations of the particular substance and that in turn implies that it is essential to produce a radioactively labeled tracer molecule of high specific radioactivity. Such tracers, particularly in the case of polypeptides and proteins, can often be conveniently produced by radioiodination.