Circular Dichroism Study on Fully Bioactive CCK-Peptides of Increasing Chain Length

Moröder, Luis; Romanò, Roberta; Weyher, Elisabeth; Svoboda, Michal; Christophe, Jean

doi:10.1515/znb-1993-1019

Cited by 9 publications

(6 citation statements)

References 9 publications

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“…A preliminary screening of the conformational preferences of CCK-15 as a function of the environment was performed by means of CD spectroscopy. As reported previously, 10 the spectrum in water lacks any of the features typical of canonical secondary structures, suggesting that CCK-15, like most short linear peptides, assumes a disordered conformation in water. While in surfactants CCK peptides of increasing chain length 10 as well as the lipoderivatized CCK-9 11 were found to exhibit CD spectra typical of β-sheet type structures, in lipid bilayers the lipo-derivatized CCK-9 assumes a helical conformation.…”

Section: Resultssupporting

confidence: 73%

“…As reported previously, 10 the spectrum in water lacks any of the features typical of canonical secondary structures, suggesting that CCK-15, like most short linear peptides, assumes a disordered conformation in water. While in surfactants CCK peptides of increasing chain length 10 as well as the lipoderivatized CCK-9 11 were found to exhibit CD spectra typical of β-sheet type structures, in lipid bilayers the lipo-derivatized CCK-9 assumes a helical conformation. 12 Similarly, the CD spectra of CCK-15 recorded in HFA/water (50:50, v/v) shows the double-well shape typical of helical structures.…”

Section: Resultssupporting

confidence: 73%

“…These interactions may account for the importance of the post-translational sulfation in terms of receptor subtype specificity. All these data yield strong evidence for a high degree of similarity between the receptor-bound CCK-8 and CCK-15, in full agreement with their identical receptor affinities . The data also validate the consensus structure as a possible bioactive conformation that can be used for further drug design.…”

Section: Resultssupporting

confidence: 67%

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Environmental Mimic of Receptor Interaction: Conformational Analysis of CCK-15 in Solution

et al. 2002

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CCK-15, a peptide derived from the 115-membered CCK preprohormone, was the object of a comparative conformational analysis by NMR spectroscopy and molecular modeling methods. NMR data in several solvents demonstrate that the propensity of the peptide to fold into a helical conformation is intrinsic, not merely a consequence of the interaction with phosphatidylcholine micelles or with a putative receptor, as suggested by a previous study on CCK-8 (Pellegrini, M.; Mierke, D. Biochemistry 1999, 38, 14775-14783.). The prevailing CCK-15 conformer in a mixture 1,1,1,3,3,3-hexafluoroacetone/water reveals that the residues common to CCK-15 and CCK-8 assume very similar conformations. Our CCK-15 structure is consistent with the model of receptor interaction proposed by Pellegrini and Mierke and discloses possible novel interactions that involve a larger area of the putative receptor. The consensus structure between CCK-15 and CCK-8 shows a good superposition of the side chains of residues 12-14 with crucial moieties of two non-peptidic CCK-A antagonists.

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Section: Resultssupporting

confidence: 73%

Section: Resultssupporting

confidence: 73%

Section: Resultssupporting

confidence: 67%

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Environmental Mimic of Receptor Interaction: Conformational Analysis of CCK-15 in Solution

et al. 2002

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“…Using this procedure 1,2-dimyristoyl-3-mercaptoglycerol was linked covalently to the TVa-maleoyl-/3-alanyl derivative of (Thr,Nle)-CCK-9, a fully active CCK analogue (Moroder et al, 1981), to produce the lipophilic CCK adduct (DM-CCK) (Romano et al, 1993b) shown in Figure 1. Since N-terminal derivatization of CCK peptides is not expected to affect significantly their bioactivity profile (Winand et al, 1991a;Moroder et al, 1993a), the lipo-CCK derivative a priori should largely retain its hormonal properties. The lipid-type structure was found to induce self-aggregation of the lipo-CCK derivative on vortexing in aqueous solution with formation of a polydispersed system of unilamellar vesicles.…”

Section: Methodsmentioning

confidence: 99%

New evidence for a membrane-bound pathway in hormone receptor binding

Moröder¹,

Romanò²,

Guba³

et al. 1993

Biochemistry

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114

120

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The fully active cholecystokinin analog (Thr,Nle)-CCK-9 was lipo-derivatized by N-terminal grafting of a dimyristoylglycerol moiety to induce tight interdigitation with cell membrane bilayers. While the parent CCK peptide was shown to interact only transiently with small unilamellar phospholipid vesicles, the lipo-CCK peptide, although self-aggregating into vesicles, inserts rapidly and quantitatively into phospholipid bilayers. Fluorescence and, even more so, NMR data are supportive for a chain reversal of the CCK moiety of the lipo derivative with embedment of the C-terminus into hydrophobic compartments of the bilayer. MD simulations allowed for a proposal of the folded form of CCK in bilayers with a helical array parallel to the interface and an amphipathic display of the side chains. In this model, the phenylalanine aromatic ring is heading the peptide molecule and may thus play a decisive role in the lateral penetration of the receptor at the water/lipid interface. In fact, despite the membrane-bound state, its binding affinity for rat pancreatic acini is comparable to that of the CCK peptide when tested after a 3-h equilibration period but 5-6-fold lower at 45 min, suggesting that the association rate is significantly lower than that of the unmodified CCK peptide. This can rationally be attributed to the tight interdigitation of the double-tailed lipo moiety with the membrane bilayer. Moreover, an escape of the lipopeptide into the extracellular aqueous phase is energetically highly unfavored; therefore, the receptor can only be reached by a membrane-bound two-dimensional migration. The observed difference in amplification between binding and amylase secretion may result from inadequate occupation of low-affinity CCK receptors, which leads then to poor couplings to G-proteins. Nevertheless the data confirm that lateral penetration of receptor structures is possible, and thus, preadsorption of peptide (neuro)hormones at the cell membrane bilayer may indeed represent the first step in the receptor recognition process.

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“…in 98% TFE (see Figure 4) is characterized by low intensity and despite its difficult interpretation, because of the presence of three aromatic residues in the relatively short sequence, it can be assigned to the presence of y-turn and/or a-helix type ordered structure [42]. Addition of metal ions at increasing concentrations to [Thr,Me]-CCK-9 in 98% TFE leads to a transition from one dominant conformational state to a second one as well evidenced by the isosbestic points at 202-203 and 216-217 nm obtained in both the Ca2+ and Tb3+ titration experiments shown in Figures 4(a) and (b).…”

Section: Binding Of Ca2' and Tb3+ To Gastrin And Cck Peptides In Aquementioning

confidence: 99%

Metal ion binding affinities of gastrin and CCK in membrane mimetic environments

Lutz

Weyher

Moröder

1995

Journal of Peptide Science

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The fully active gastrin and CCK analogues [Nle 15]-gastrin-17 and [Nle, Thr]-CCK-9 were analysed for their Ca2+ and Tb3+ affinities in various membrane mimetic conditions. In TFE both gastrin and CCK exhibited high affinities for calcium and terbium. At saturation level identical metal ion/peptide ratios were determined with Ca2+ and Tb3+, i.e. R = 3 for gastrin and R = 1 for CCK, confirming the very similar coordination properties of the two metal ions. The conformational effects of both metal ions were found to be very similar with a disordering effect in the case of gastrin and a conformational transition to beta-turn type structure in the case of CCK. In order to mimic more properly physiological conditions, similar experiments were performed in the presence of phospholipid bilayers. No interaction of the peptides with the bilayers was observed even in the presence of mmolar Ca2+ concentrations. Induced lipid interaction via N-terminal lipo-derivatization of gastrin and CCK allowed to translocate quantitatively the two hormones into phospholipid bilayers and to examine the effect of extravesicular Ca2+ on the conformation of the peptide headgroups and on their display at the water/lipid interphase. The CCK moiety of the lipo-CCK inserted into phospholipid bilayers interacts with the lipid phase and addition of Ca2+ enhances the clustering of the peptide headgroups in a more beta-sheet type conformation. Conversely, insertion of lipo-gastrin into the bilayers leads to full exposure of the gastrin headgroup to the bulk water in predominantly random coil structure. Again Ca2+ provokes aggregation. As the lipo-peptide/phospholipid system still represents only an artificial model, it remains hazardous to derive a biological relevance from these data. The significantly higher affinity of lanthanide ions than Ca2+ for the peptides could well play a role in the inhibitory activity of lanthanum on the signal transduction of the CCK family of hormones.

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Circular Dichroism Study on Fully Bioactive CCK-Peptides of Increasing Chain Length

Cited by 9 publications

References 9 publications

Environmental Mimic of Receptor Interaction: Conformational Analysis of CCK-15 in Solution

Environmental Mimic of Receptor Interaction: Conformational Analysis of CCK-15 in Solution

New evidence for a membrane-bound pathway in hormone receptor binding

Metal ion binding affinities of gastrin and CCK in membrane mimetic environments

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