Modification of the C-terminal octapeptide of cholecystokinin with a high-specific-activity lodinated imidoester: Preparation, characterization, and binding to isolated pancreatic acinar cells
✍ Scribed by Melvin Praissman; Richard S. Izzo; Jesse M. Berkowitz
- Publisher
- Elsevier Science
- Year
- 1982
- Tongue
- English
- Weight
- 745 KB
- Volume
- 121
- Category
- Article
- ISSN
- 0003-2697
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✦ Synopsis
Both radiotrace-labeled and high-specific-activity 'Z51-labeled derivatives of the biologically active C-terminal octapeptide of cholecystokinin (CCK-8) were prepared by reaction with the iodinated form of the imidoester (HE), methyl p-hydroxybenzimidate. Following gel and ionexchange chromatography the purified IIE-CCK-8 derivative displayed a new peak in the ultraviolet at 320 nm, and was equally potent as CCK-8 in stimulating cyclic GMP production in dispersed pancreatic acinar cells from guinea pig. The high-specific-activity derivative ('*'HE-CCK-8) was prepared with carrier-free iodine-l 25 and had a specific activity exceeding 2000 pCi/nmol. A sensitive radioimmunoassay using this derivative and a specific antisera was capable of detecting CCK-8, caerulein, and CCK-33, but not gastrin and desulfated CCK-8. Finally, "'IIE-CCK-8 bound specifically to dispersed acinar cells, and was competitively inhibited by CCK-8 but not by other nonrelated peptide hormones.