Replacement of Tyr-SO3H by a p-carboxymethyl-phenylalanine in a CCK8-derivative preserves its high affinity for CCK-B receptor.
The sulfated tyrosine present in the sequence of CCK8 Asp26-Tyr(SO3H)-Met-Gly-Trp-Met-Asp-PheNH2, seems to play a critical role in the recognition of CCK-A binding sites. In this work, we have investigated whether the presence of an anionic charge on the tyrosine moiety is strictly necessary and whether the sulfate moiety interacts with a divalent cation in the receptor subsite. For this purpose, the novel amino acids (L,D)Phe(p-CH2CO2H) and (L,D) Phe(p-CH2CONHOH), as well as their L-resolved forms were introduced into the sequence of Ac[X27, Nle28, Nle31]-CCK27-33 by solid phase method. The biological activities of these new derivatives were compared to two almost equiactive analogues of CCK8, Ac[Phe(p-CH2SO3H)27, Nle28, Nle31]-CCK27-33 and Boc[Nle28, Nle31]-CCK27-33 (BDNL) and to the nonsulfated analogue of the latter peptide (BDNL NS). All these new CCK-related analogues behave as agonists in stimulating pancreatic amylase release and display high affinity for brain binding sites (KI approximately 3-11 nM) but the only peptides which retain affinity for CCK-A receptors (KI approximately 20 nM) are those containing a p-carboxymethyl phenylalanine. Thus, introduction of this amino acid under an esterified form on the side chain, into specific and potent CCK-B agonists could allow compounds endowed with good bioavailabilities to be obtained.
McCort-Tranchepain
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I
UFR of Pharmaceutic and Biologic Sciences, Department of Organic Chemistry, U266-INSERM, UA498 CNRS, Paris, France.
Ficheux
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Durieux
C
C
Roques
B P
BP
D000595:Amino Acid Sequence; D000681:Amylases / Q000378:metabolism; D000818:Animals; D001665:Binding Sites; D001681:Biological Assay; D001921:Brain / Q000378:metabolism; D006168:Guinea Pigs; D008969:Molecular Sequence Data; D010179:Pancreas / Q000201:enzymology / Q000378:metabolism; D010649:Phenylalanine / Q000031:analogs & derivatives* / Q000737:chemistry; D011949:Receptors, Cholecystokinin / Q000737:chemistry / Q000378:metabolism*; D012844:Sincalide / Q000031:analogs & derivatives* / Q000737:chemistry / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry
D011949:Receptors, Cholecystokinin; C075824:4-carboxymethylphenylalanine; D014443:Tyrosine; D010649:Phenylalanine; D000681:Amylases; D012844:Sincalide