Abstract
For cholecystokinin (CCK)-specific radioimmuoassay (RIA), CCK-33 and CCK-8 were iodinated by 1251-Bolton-Hunter (BH) reagent. Both RIAs using 125I-BH-CCK-33 and 1251-BHCCK-8 were identical in sensitivity and specificity. On the other hand, the RIA using 125I-BHCCK-33 allowed us to measure CCK in plasma without prior extraction of plasma samples, while extraction of plasma was required for RIA using 125I-BH-CCK-8. Histidine residues of synthetic human parathyroid (hPTH) 1-34 were iodinated by chloramine T for N-terminal PTH RIA. The specific radioactivity of the 125I-hPTH1-34 was 110μCi/μg and immunological activity was almost maintained by the iodination.
