title: Homogeneous mono-(125)i-insulins. Preparation and characterization of mono-(125)i-(tyr a14)-and mono-(125)i-(tyr a19)-insulin.
abstract: Mono-(125)I-(Tyr A19)-insulin (Mono*A19) was prepared by iodinating MC porcine insulin with (125)I in acid medium using iodate (as oxidizing agent), followed by anion-exchange chromatography. Mono-(125)I-(Tyr A14)-insulin (Mono*A14) was prepared by iodinating MC porcine insulin with (125)I, using H(2)O(2)/lactoperoxidase at neutral pH, followed by anion-exchange chromatography. The specific radioactivities were in the ranges of 120-200 and 220-300 mCi/mg for Mono*A19 and Mono*A14, respectively. Analyses of the intramolecular distributions of (125)I demonstrated that the preparations were 97-98% radiochemically pure. In both preparations, 98-99% of the radioactivity was capable of binding to insulin antibodies for up to 6 months of storage of the tracers. The IRI concentration decreased with the duration of storage. The greatest observed fall in IRI concentration was 70%. The ime course could be explained by the assumption that the disintegration of a (125)I-nucleus destroys the immunoreactivity of the insulin molecule in which the decay occurs.
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex; D004355:Drug Stability; D007328:Insulin / Q000031:analogs & derivatives* / Q000276:immunology; D007330:Insulin Antibodies; D007457:Iodine Radioisotopes; D007553:Isotope Labeling / Q000379:methods; D046911:Macromolecular Substances; D011863:Radioimmunoassay; D013552:Swine
chemical_list: D000936:Antigen-Antibody Complex; D007328:Insulin; D007330:Insulin Antibodies; D007457:Iodine Radioisotopes; D046911:Macromolecular Substances; C008147:insulin, iodo-