Chelating groups, radiolabeled

Figure 20.18 The bifunctional chelating reagent DTPA may be used to modify amine groups on antibody molecules, forming amide bond linkages. Indium-111 then may be complexed to the chelator group to create a radiolabeled-targeting reagent.

Of course, the signal that we observe (e.g., counts/minute) is directly proportional to the number of chelators present. That is, the fraction of radiolabel that is bound to a protein molecule containing X chelating groups is ... 

Methods based on radiolabels continue to hold an important place in routine analysis and in research related to clinical testing. The main techniques included in this group are radioimmunoassy (RIA), immunoradiometric assay (IRMA), and scintillation proximity assay (SPA). Many researchers in this field use short-lived radioisotopes and chelating agents in antibody labeling.139 The most popular types of immunoassay are methods that use enzymatic labels the enzyme-linked immunosorbent assay (ELISA), the enzyme-monitored immunotest (EMIT), the competitive binding enzyme immunoassay (EIA), and the immunoenzymometric assay (IEMA). 

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