In 1959, Yalow and Berson used insulin labeled with radioactive iodine to develop a quantitative immunological method for determining the amount of insulin in human plasma. Their method depends upon a competition between insulin labeled with radioactive iodine (I131) and unlabeled insulin from plasma for a fixed and limited number of specific binding sites on the antibody to insulin. The amount of the labeled insulin bound to the antibody is inversely proportional to the amount of insulin in the plasma sample. Their method, which is so elegantly simple in concept, is made possible by the ability to detect with ease extremely low levels of radioactivity, and by the exquisite specificity of an antibody capable of specifically binding the analyte. Such a combination of sensitivity and specificity is the basis of this versatile analytical tool called radioimmunoassay (RIA).
KeywordsRadioactive Iodine Unbind Fraction FEBS Letter Heterogeneous Phase Immunoenzymatic Assay
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