1
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Lameiras P, Nuzillard JM. Tailoring the nuclear Overhauser effect for the study of small and medium-sized molecules by solvent viscosity manipulation. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2021; 123:1-50. [PMID: 34078536 DOI: 10.1016/j.pnmrs.2020.12.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 11/06/2020] [Accepted: 12/02/2020] [Indexed: 06/12/2023]
Abstract
The nuclear Overhauser effect (NOE) is a consequence of cross-relaxation between nuclear spins mediated by dipolar coupling. Its sensitivity to internuclear distances has made it an increasingly important tool for the determination of through-space atom proximity relationships within molecules of sizes ranging from the smallest systems to large biopolymers. With the support of sophisticated FT-NMR techniques, the NOE plays an essential role in structure elucidation, conformational and dynamic investigations in liquid-state NMR. The efficiency of magnetization transfer by the NOE depends on the molecular rotational correlation time, whose value depends on solution viscosity. The magnitude of the NOE between 1H nuclei varies from +50% when molecular tumbling is fast to -100% when it is slow, the latter case corresponding to the spin diffusion limit. In an intermediate tumbling regime, the NOE may be vanishingly small. Increasing the viscosity of the solution increases the motional correlation time, and as a result, otherwise unobservable NOEs may be revealed and brought close to the spin diffusion limit. The goal of this review is to report the resolution of structural problems that benefited from the manipulation of the negative NOE by means of viscous solvents, including examples of molecular structure determination, conformation elucidation and mixture analysis (the ViscY method).
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Affiliation(s)
- Pedro Lameiras
- Université de Reims Champagne-Ardenne, CNRS, ICMR UMR 7312, 51097 Reims, France
| | - Jean-Marc Nuzillard
- Université de Reims Champagne-Ardenne, CNRS, ICMR UMR 7312, 51097 Reims, France
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2
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Miyanabe K, Yamashita T, Abe Y, Akiba H, Takamatsu Y, Nakakido M, Hamakubo T, Ueda T, Caaveiro JMM, Tsumoto K. Tyrosine Sulfation Restricts the Conformational Ensemble of a Flexible Peptide, Strengthening the Binding Affinity for an Antibody. Biochemistry 2018; 57:4177-4185. [DOI: 10.1021/acs.biochem.8b00592] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Kazuhiro Miyanabe
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Takefumi Yamashita
- Laboratory for Systems Biology and Medicine, RCAST, The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan
| | - Yoshito Abe
- Laboratory of Protein Structure, Function, and Design, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi,
Higashi-ku, Fukuoka 812-8582, Japan
| | - Hiroki Akiba
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Laboratory of Pharmacokinetic Optimization, Center for Drug Design Research, National Institutes of Biomedical Innovation, Health and Nutrition, 7-6-8 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan
| | - Yuichiro Takamatsu
- Quantitative Biology and Medicine, Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - Makoto Nakakido
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Takao Hamakubo
- Quantitative Biology and Medicine, Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, Meguro-ku, Tokyo 153-8904, Japan
| | - Tadashi Ueda
- Laboratory of Protein Structure, Function, and Design, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi,
Higashi-ku, Fukuoka 812-8582, Japan
| | - Jose M. M. Caaveiro
- Laboratory of Global Healthcare, Graduate School of Pharmaceutical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi-ku, Fukuoka 812-8582, Japan
| | - Kouhei Tsumoto
- Department of Chemistry and Biotechnology, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Department of Bioengineering, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Laboratory of Pharmacokinetic Optimization, Center for Drug Design Research, National Institutes of Biomedical Innovation, Health and Nutrition, 7-6-8 Saito-Asagi, Ibaraki, Osaka 567-0085, Japan
- Laboratory of Medical Proteomics, Institute of Medical Science, The University of Tokyo, 4-6-1 Shirokanedai, Minato-ku, Tokyo 108-8639, Japan
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3
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Lesma G, Salvadori S, Airaghi F, Murray TF, Recca T, Sacchetti A, Balboni G, Silvani A. Structural and biological exploration of phe(3)-phe(4)-modified endomorphin-2 peptidomimetics. ACS Med Chem Lett 2013; 4:795-9. [PMID: 24900748 DOI: 10.1021/ml400189r] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2013] [Accepted: 07/11/2013] [Indexed: 12/24/2022] Open
Abstract
This study reports on our ongoing investigation on hybrid EM-2 analogues, in which the great potential of β-amino acids was exploited to generate multiple conformational modifications at the key positions 3 and 4 of the parent peptide. The effect on the opioid binding affinity was evaluated, by means of ligand stimulated binding assays, which indicated a high nanomolar affinity toward the μ-receptor, with appreciable μ/δ selectivity, for some of the new compounds. The three-dimensional properties of the high affinity μ opioid receptor (MOR) ligands were investigated by proton nuclear magnetic resonance, molecular dynamics, and docking studies. In solution, the structures showed extended conformations, which are in agreement with the commonly accepted pharmacophore model for EM-2. From docking studies on an active form of the MOR model, different ligand-receptor interactions have been identified, thus confirming the ability of active compounds to assume a biologically active conformation.
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Affiliation(s)
- Giordano Lesma
- Dipartimento di Chimica, Università degli Studi di Milano, via C. Golgi, 19, 20133 Milano, Italy
| | - Severo Salvadori
- Dipartimento di Scienze Farmaceutiche, Università degli Studi di Ferrara, via Fossato
di Mortara 17-19, 44100 Ferrara, Italy
| | - Francesco Airaghi
- Dipartimento di Chimica, Università degli Studi di Milano, via C. Golgi, 19, 20133 Milano, Italy
| | - Thomas F. Murray
- Department of Pharmacology, Creighton University School of Medicine, Omaha, Nebraska 68102,
United States
| | - Teresa Recca
- Dipartimento di Chimica, Università degli Studi di Milano, via C. Golgi, 19, 20133 Milano, Italy
| | - Alessandro Sacchetti
- Dipartimento
di Chimica, Materiali ed Ingegneria Chimica ‘Giulio Natta’, Politecnico di Milano, p.zza Leonardo
da Vinci 32, 20133 Milano, Italy
| | - Gianfranco Balboni
- Dipartimento di Scienze della Vita e dell’Ambiente, Università degli Studi di Cagliari, Via Ospedale
72, 09124 Cagliari, Italy
| | - Alessandra Silvani
- Dipartimento di Chimica, Università degli Studi di Milano, via C. Golgi, 19, 20133 Milano, Italy
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4
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Conformational properties of a pyridyl-substituted cinnamic acid studied by NMR measurements and computations. J Mol Struct 2013. [DOI: 10.1016/j.molstruc.2012.10.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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5
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Synthesis, pharmacological evaluation and conformational investigation of endomorphin-2 hybrid analogues. Mol Divers 2012; 17:19-31. [DOI: 10.1007/s11030-012-9399-5] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 09/24/2012] [Indexed: 01/26/2023]
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6
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Borics A, Mallareddy JR, Timári I, Kövér KE, Keresztes A, Tóth G. The Effect of Pro2 Modifications on the Structural and Pharmacological Properties of Endomorphin-2. J Med Chem 2012; 55:8418-28. [DOI: 10.1021/jm300836n] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Affiliation(s)
- Attila Borics
- Institute of Biochemistry, Biological
Research Center of the Hungarian Academy of Sciences, P.O. Box 521,
H-6701 Szeged, Hungary
| | - Jayapal R. Mallareddy
- Institute of Biochemistry, Biological
Research Center of the Hungarian Academy of Sciences, P.O. Box 521,
H-6701 Szeged, Hungary
| | - István Timári
- Department of Chemistry, University
of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary
| | - Katalin E. Kövér
- Department of Chemistry, University
of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary
| | - Attila Keresztes
- Institute of Biochemistry, Biological
Research Center of the Hungarian Academy of Sciences, P.O. Box 521,
H-6701 Szeged, Hungary
| | - Géza Tóth
- Institute of Biochemistry, Biological
Research Center of the Hungarian Academy of Sciences, P.O. Box 521,
H-6701 Szeged, Hungary
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7
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Mallareddy JR, Borics A, Keresztes A, Kövér KE, Tourwé D, Tóth G. Design, synthesis, pharmacological evaluation, and structure-activity study of novel endomorphin analogues with multiple structural modifications. J Med Chem 2011; 54:1462-72. [PMID: 21287991 DOI: 10.1021/jm101515v] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This study reports on new proteolytically stable, pharmacologically active endomorphin analogues, incorporating Dmt(1), Achc(2), pFPhe(4), or βMePhe(4) unnatural amino acids. Consistent with earlier results, it was found that the analogues carrying Dmt(1) and Achc(2) residues displayed the highest μ-opioid receptor affinities, depending upon the configuration of the incorporated Achc(2). Combination of such derivatives with pFPhe(4) or βMePhe(4) yielded further compounds with variable binding potencies. Combined application of Dmt(1), cis-(1S,2R)Achc(2), and pFPhe(4) (compound 16) resulted in the most potent analogue. Ligand stimulated [(35)S]GTPγS binding assays indicated that the analogues retained their agonist activities and opioid receptor specificities. NMR and molecular modeling studies of the analogues containing βMePhe(4) or pFPhe(4) confirmed the predominance of bent structures, however, it is apparent that bent structures are energetically more favored than random/extended structures for all studied compounds.
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Affiliation(s)
- Jayapal Reddy Mallareddy
- Institute of Biochemistry , Biological Research Center, Hungarian Academy of Sciences, PO Box 521, H-6701 Szeged, Hungary
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8
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Structural comparison of μ-opioid receptor selective peptides confirmed four parameters of bioactivity. J Mol Graph Model 2010; 28:495-505. [DOI: 10.1016/j.jmgm.2009.11.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2009] [Revised: 11/24/2009] [Accepted: 11/27/2009] [Indexed: 11/18/2022]
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9
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Agnes RS, Ying J, Kövér KE, Lee YS, Davis P, Ma SW, Badghisi H, Porreca F, Lai J, Hruby VJ. Structure-activity relationships of bifunctional cyclic disulfide peptides based on overlapping pharmacophores at opioid and cholecystokinin receptors. Peptides 2008; 29:1413-23. [PMID: 18502541 PMCID: PMC2601673 DOI: 10.1016/j.peptides.2008.03.022] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2008] [Revised: 03/26/2008] [Accepted: 03/27/2008] [Indexed: 11/24/2022]
Abstract
Prolonged opioid exposure increases the expression of cholecystokinin (CCK) and its receptors in the central nervous system (CNS), where CCK may attenuate the antinociceptive effects of opioids. The complex interactions between opioid and CCK may play a role in the development of opioid tolerance. We designed and synthesized cyclic disulfide peptides and determined their agonist properties at opioid receptors and antagonist properties at CCK receptors. Compound 1 (Tyr-c[d-Cys-Gly-Trp-Cys]-Asp-Phe-NH(2)) showed potent binding and agonist activities at delta and mu opioid receptors but weak binding to CCK receptors. The NMR structure of the lead compound displayed similar conformational features of opioid and CCK ligands.
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Affiliation(s)
- Richard S. Agnes
- Department of Chemistry, University of Arizona, Tucson, AZ 85721
| | - Jinfa Ying
- Department of Chemistry, University of Arizona, Tucson, AZ 85721
| | - Katalin E. Kövér
- Department of Chemistry, University of Debrecen, H-4010 Debrecen, P.O. Box 21, Egyetem tér 1, Hungary
| | - Yeon Sun Lee
- Department of Chemistry, University of Arizona, Tucson, AZ 85721
| | - Peg Davis
- Department of Pharmacology, University of Arizona, Tucson, AZ 85724
| | - Shou-wu Ma
- Department of Pharmacology, University of Arizona, Tucson, AZ 85724
| | - Hamid Badghisi
- Department of Pharmacology, University of Arizona, Tucson, AZ 85724
| | - Frank Porreca
- Department of Pharmacology, University of Arizona, Tucson, AZ 85724
| | - Josephine Lai
- Department of Pharmacology, University of Arizona, Tucson, AZ 85724
| | - Victor J. Hruby
- Department of Chemistry, University of Arizona, Tucson, AZ 85721
- To whom correspondence should be addressed: Victor J. Hruby, Department of Chemistry, University of Arizona, Tucson, AZ 85721, USA. Phone: (520) 621-6332. Fax: (520) 621-8407.,
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10
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Kumar M, Reeve JR, Hu W, Miller LJ, Keire DA. The micelle-associated 3D structures of Boc-Y(SO3)-Nle-G-W-Nle-D-2-phenylethylester (JMV-180) and CCK-8(s) share conformational elements of a calculated CCK1 receptor-bound model. J Med Chem 2008; 51:3742-54. [PMID: 18540665 DOI: 10.1021/jm701401j] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
JMV-180 ( 1) and CCK-8(s) are high affinity ligands at the CCK 1 receptor that have similar and different actions via this receptor. Here we calculate the tertiary structure of 1 or CCK-8(s) in the presence of dodecylphosphocholine micelles at pH 5.0 and 35 degrees C from 2D (1)H NMR data recorded at 600 MHz. The NMR derived 3D structures of 1 and CCK-8(s) share a common type I beta-turn around residues Nle3/M3 and G4 and diverge from each other structurally at the N- and C-termini. The fluorescence and circular dichroism spectral properties of these peptides are consistent with their NMR derived structures. The structures determined in the presence of DPC micelles are compared to available models of 1 or CCK-8(s) bound to the CCK 1 receptor. For CCK and 1, these comparisons show that DPC micelle associated structures duplicate some important aspects of the models calculated from cross-linking derived constraints at the CCK 1 receptor.
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Affiliation(s)
- Mohanraja Kumar
- CURE: Digestive Diseases Research Center, VA Greater Los Angeles Healthcare System, Los Angeles, California 90073, USA
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11
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Tyndall JDA, Pfeiffer B, Abbenante G, Fairlie DP. Over One Hundred Peptide-Activated G Protein-Coupled Receptors Recognize Ligands with Turn Structure. Chem Rev 2005; 105:793-826. [PMID: 15755077 DOI: 10.1021/cr040689g] [Citation(s) in RCA: 176] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Affiliation(s)
- Joel D A Tyndall
- Center for Drug Design and Development, Institute for Molecular Bioscience, University of Queensland, Brisbane, Qld 4072, Australia
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12
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Giragossian C, Schaschke N, Moroder L, Mierke DF. Conformational and Molecular Modeling Studies of β-Cyclodextrin−Heptagastrin and the Third Extracellular Loop of the Cholecystokinin 2 Receptor. Biochemistry 2004; 43:2724-31. [PMID: 15005607 DOI: 10.1021/bi035509w] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The conformational features of a conjugate of the C-terminus of human gastrin (HG[11-17]), the shortest gastrin sequence retaining biological function, with beta-cyclodextrin ([Nle(15)]-HG[11-17]-betaCD) were determined by NMR spectroscopy in an aqueous solution of dodecylphosphocholine (DPC) micelles. The peptide-betaCD conjugate displays a binding affinity and activation profile comparable to those of HG[11-17] at the cholecysokinin 2 (CCK(2)) receptor, the G protein-coupled receptor responsible for the gastrointestinal function of gastrin. The structure of the peptide consisted of a well-defined beta-turn between Gly(13) and Asp(16) of gastrin. The structural preferences of [Nle(15)]-HG[11-17]-betaCD in DPC micelles and the 5-doxylstearate-induced relaxation of the (1)H NMR resonances support a membrane-associated receptor recognition mechanism. Addition of [Nle(15)]-HG[11-17]-betaCD to the third extracellular loop domain of the CCK(2) receptor, CCK(2)-R(352-379), generated a number of intermolecular nuclear Overhauser enhancements (NOEs) and chemical shift perturbations. NOE-restrained MD simulations of the [Nle(15)]-HG[11-17]-betaCD-CCK(2)-R complex produced a topological orientation in which the C-terminus was located in a shallow hydrophobic pocket near the confluence of TM2 and -3. Despite the steric bulk and physicochemical properties of betaCD, the [Nle(15)]-HG[11-17]-betaCD-CCK(2)-R complex is similar to the CCK-8-CCK(2)-R complex determined previously, providing insight into the mode of ligand binding and the role of electrostatic interactions.
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Affiliation(s)
- Craig Giragossian
- Department of Chemistry, Division of Biology and Medicine, Brown University, Providence, Rhode Island 02912, USA
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13
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Palian MM, Boguslavsky VI, O'Brien DF, Polt R. Glycopeptide-membrane interactions: glycosyl enkephalin analogues adopt turn conformations by NMR and CD in amphipathic media. J Am Chem Soc 2003; 125:5823-31. [PMID: 12733923 DOI: 10.1021/ja0268635] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Four enkephalin analogues (Tyr-D-Thr-Gly-Phe-Leu-Ser-CONH(2), 1, and the related O-linked glycopeptides bearing the monosaccharide beta-glucose, 2, the disaccharide beta-maltose, 3, and the trisaccharide beta-maltotriose, 4) were synthesized, purified by HPLC, and biophysical studies were conducted to examine their interactions with membrane model systems. Glycopeptide 2 has been previously reported to penetrate the blood-brain barrier (BBB), and produce potent analgesia superior to morphine in mice (J. Med. Chem.2000, 43, 2586-90 and J. Pharm. Exp. Ther. 2001, 299, 967-972). The parent peptide and its three glycopeptide derivatives were studied in aqueous solution and in the presence of micelles using 2-D NMR, CD, and molecular mechanics (Monte Carlo studies). Consistent with previous conformational studies on cyclic opioid agonist glycopeptides, it was seen that glycosylation did not significantly perturb the peptide backbone in aqueous solution, but all four compounds strongly associated with 5-30 mM SDS or DPC micelles, and underwent profound membrane-induced conformational changes. Interaction was also observed with POPC:POPE:cholesterol lipid vesicles (LUV) in equilibrium dialysis experiments. Although the peptide backbones of 1-4 possessed random coil structures in water, in the presence of the lipid phase they each formed a nearly identical pair of structures, all with a stable beta-turn motif at the C-terminus. Use of spin labels (Mn(2+) and 5-DOXYL-stearic acid) allowed for the determination of the position and orientation of the compounds relative to the surface of the micelle.
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Affiliation(s)
- Michael M Palian
- Carl S. Marvel Laboratories, Department of Chemistry, The University of Arizona, Tucson, Arizona 85721, USA
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14
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Dawson ES, Henne RM, Miller LJ, Lybrand TP. Moleular models for cholecystokinin-A receptor. PHARMACOLOGY & TOXICOLOGY 2002; 91:290-6. [PMID: 12688371 DOI: 10.1034/j.1600-0773.2002.910605.x] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Numerous techniques have been used to elucidate the structural basis for interaction of cholecystokinin (CCK)-related peptides with their hormone-binding receptor, the CCK-A receptor (CCK-AR), including structure-activity relationship studies, site-directed mutagenesis, photoaffinity-labeling, and solution NMR analysis of both CCK peptide ligands and peptide fragments derived from the CCK-A receptor. Different structural models have been developed for the peptide-receptor complexes using various subsets of the available experimental data (Giragossian & Mierke 2001; Ding et al. 2002; Escrieut et al. 2002). Here, we review details of the various models and evaluate the impact of selected experimental data sets on model development.
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Affiliation(s)
- Eric S Dawson
- Department of Chemistry, Vanderbilt University, Center for Structural Biology, Nashville, TN 37235-1822, USA
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15
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Giragossian C, Stone S, Papini AM, Moroder L, Mierke DF. Conformational and molecular modeling studies of sulfated cholecystokinin-15. Biochem Biophys Res Commun 2002; 293:1053-9. [PMID: 12051766 DOI: 10.1016/s0006-291x(02)00334-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Conformational features of the C-terminal carboxyamidated pentadecapeptide of CCK (S(19)HRISDRD[SO(4)]-YMGWMDF(33)-NH(2)) were determined by NMR spectroscopy in a zwitterionic membrane-mimetic solvent system, composed of DPC micelles. The C-terminal octapeptide consisted of a well-defined pseudohelix that was nearly identical to the structure previously reported for nonsulfated CCK-8 in the same solvent system. N-terminal amino acids of CCK-15 were highly disordered, with no clear conformational preference. Extensive NOE-restrained molecular dynamics simulations of the CCK-15/CCK(1)-R complex suggested that almost all the experimentally determined intermolecular contact points provided by NMR, site-directed mutagenesis, and photoaffinity labeling could be simultaneously satisfied, when the N-terminus of the ligand is placed in close spatial proximity to the N-terminus of the receptor.
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Affiliation(s)
- Craig Giragossian
- Department of Chemistry, Division of Biology & Medicine, Brown University, Providence, RI 02912, USA
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