Synthesis of potent heptapeptide analogs of cholecystokinin

Abstract

Nine new analogues of acetyl-CCK-heptapeptide (Ac-Tyr(SO3H)2-Met3-Gly4-Trp5-Met6-Asp7-Phe8-NH2 ) were synthesized by solid-phase methodology. In a first series, the Asp7 residue was replaced by hydroxy amino acid sulfate esters. In another series, Gly4 was substituted by D-Ala, while Trp5 and Met6 were replaced by their D enantiomer. The introduction of the sulfate ester was performed with a new, mild, crystalline, and stable reagent, pyridinium acetyl sulfate. Each analogue that contained Tyr(SO3H)2 and a hydroxy amino acid sulfate ester [Ser(SO3H), Thr(SO3H), or Hyp(SO3H)] in position 7 proved to be more potent (1.9, 1.7, and 3.0 times, respectively) than CCK-8 in vitro (isolated gallbladder strips). While devoid of gastrin-like activity in vivo, these analogues had potent anticonvulsive activity. The analogues containing a D-amino acid residue were less potent than the parent compound in vitro. The D-Ala4 replacement, however, yielded a compound that was 40% as potent as CCK-8 in the in vitro test but showed prolonged duration of action on sphincter Oddi. While the 7-substituted Ac-CCK heptapeptides are among the most potent CCK analogues reported so far, the D-Ala4 replacement resulted, for the first time, in prolonged activity in vivo.

Toward a framework for sulfoproteomics: Synthesis and characterization of sulfotyrosine‐containing peptides

“…Irrespective of the reagent used, chemical sulfation occurs preferentially at the alcoholic hydroxyl groups of Ser, Thr, and hydroxyPro residues rather than at the phenolic hydroxyl groups of Tyr residues. 87,90,97 Furthermore, in the presence of Cys residues, formation of Cys thiosulfate has also been observed. 87 The undesired sulfation of these residues can sometimes be avoided by a segment synthesis strategy 89 ; however, the use of orthogonally removable protecting groups provides a more general approach to solving this problem.…”

Synthesis of sulfated bioactive peptides using immobilized arylsulfotransferase from Eubacterium sp.

“…The chemical introduction of a sulfate group into the tyrosine residues of peptides and proteins by the classical pyridine-SO3 causes many side reactions in sensitive amino acids such as methionine, tryptophan, cystein and asparagine/glutamine (Toth et al 1985). Mild sulfation reagents, such as pyridinium acetyl sulfate or diciclohexylcarbodiimide-HzSOq, have been developed to circumvent these problems (Wieland et al, 1972;Penke et al, 1984). However it is not possible to discriminate between phenolic hydroxyls like tyrosine residues and alcoholic ones, like serine, threonine or hydroxyprolin residues.…”

In Vitro and in Vivo Nuclear Factor-κB Inhibitory Effects of the Cell-Penetrating Penetratin Peptide

“…For the internalization studies, the peptides were labeled with fluorescein isothiocyanate (FITC; Sigma-Aldrich Hungary Ltd., Budapest, Hungary) as described by Fü löp et al (2001). Cholecystokinin-octapeptide (CCK) was also prepared in our laboratory by method of Penke et al (1984).…”