Use of N,O-bis-Fmoc-d-Tyr-ONSu for introduction of an oxidative iodination site into cholecystokinin family peptides |
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Authors: | STEPHEN P POWERS DELIA I PINON LAURENCE J MILLER |
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Abstract: | We report the synthesis of a new reagent for the introduction of an oxidative iodination site into the amino terminus of acid-labile peptides, and the use of this reagent to synthesize a novel affinity-labeling probe for the cholecystokinin (CCK) receptor. The acylation reagent, N,O-bis-fluorenylmethyloxycarbonyl-d -tyrosine hydroxysuccinimide ester, utilizes base-labile protection of both the alpha amino group and the aromatic ring hydroxyl. This can be safely removed to expose a cross-linkable free amino group on the aminopeptidase-resistant d -enantiomer of tyrosine. The synthetic probe, d -Tyr-Gly-Asp-Tyr(OSO3H)-Nle-Gly-Trp-Nle-Asp-Phe-NH2, was fully biologically active, could be radioiodinated to high-specific radioactivity (2000 Ci/mmol), bound with high affinity to the pancreatic CCK receptor, and covalently labeled the hormone-binding site. This reagent should be useful for the synthesis of a wide variety of analogues of CCK and other acid-labile peptides. |
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Keywords: | cholecystokinin iodination |
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