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Vila-Julià G, Rubio-Martinez J, Perez JJ. Assessment of the bound conformation of bombesin to the BB1 and BB2 receptors. Int J Biol Macromol 2024; 255:127843. [PMID: 37956803 DOI: 10.1016/j.ijbiomac.2023.127843] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 10/31/2023] [Accepted: 10/31/2023] [Indexed: 11/15/2023]
Abstract
Bombesin is an endogenous peptide involved in a wide spectrum of physiological activities ranging from satiety, control of circadian rhythm and thermoregulation in the central nervous system, to stimulation of gastrointestinal hormone release, activation of macrophages and effects on development in peripheral tissues. Actions of the peptide are mediated through the two high affinity G-protein coupled receptors BB1R and BB2R. Under pathophysiological conditions, these receptors are overexpressed in many different types of tumors, such as prostate cancer, breast cancer, small and non-small cell lung cancer and pancreatic cancer. This observation has been used for designing cell markers, but it has not been yet exploited for therapeutical purposes. Despite the enormous biological interest of the peptide, little is known about the stereochemical features that contribute to their activity. On the one hand, mutagenesis studies identified a few receptor residues important for high bombesin affinity and on the other, a few studies focused on the relevance of diverse residues of the peptide for receptor activation. Models of the peptide bound to BB1R and BB2R can be helpful to improve our understanding of the stereochemical features granting bombesin activity. Accordingly, the present study describes the computational process followed to construct such models by means of Steered Molecular Dynamics, using models of the peptide and its receptors. Present results provide new insights into the structure-activity relationships of bombesin and its receptors, as well as render an explanation for the differential binding affinity observed towards BB1R and BB2R. Finally, these models can be further exploited to help for designing novel small molecule peptidomimetics with improved pharmacokinetics profile.
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Affiliation(s)
- Guillem Vila-Julià
- Department of Materials Science and Physical Chemistry, University of Barcelona and the Institut de Recerca en Quimica Teorica i Computacional (IQTCUB), Barcelona, Spain; Department of Chemical Engineering, Universitat Politecnica de Catalunya- Barcelona Tech., Av. Diagonal, 647, 08028 Barcelona, Spain
| | - Jaime Rubio-Martinez
- Department of Materials Science and Physical Chemistry, University of Barcelona and the Institut de Recerca en Quimica Teorica i Computacional (IQTCUB), Barcelona, Spain
| | - Juan J Perez
- Department of Chemical Engineering, Universitat Politecnica de Catalunya- Barcelona Tech., Av. Diagonal, 647, 08028 Barcelona, Spain.
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2
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Palmioli A, Nicolini G, Tripodi F, Orsato A, Ceresa C, Donzelli E, Arici M, Coccetti P, Rocchetti M, La Ferla B, Airoldi C. Targeting GRP receptor: Design, synthesis and preliminary biological characterization of new non-peptide antagonists of bombesin. Bioorg Chem 2021; 109:104739. [PMID: 33626451 DOI: 10.1016/j.bioorg.2021.104739] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2020] [Revised: 02/03/2021] [Accepted: 02/04/2021] [Indexed: 01/29/2023]
Abstract
We report the rational design, synthesis, and in vitro preliminary evaluation of a new small library of non-peptide ligands of Gastrin Releasing Peptide Receptor (GRP-R), able to antagonize its natural ligand bombesin (BN) in the nanomolar range of concentration. GRP-R is a transmembrane G-protein coupled receptor promoting the stimulation of cancer cell proliferation. Being overexpressed on the surface of different human cancer cell lines, GRP-R is ideal for the selective delivery to tumor cells of both anticancer drug and diagnostic devices. What makes very challenging the design of non-peptide BN analogues is that the 3D structure of the GRP-R is not available, which is the case for many membrane-bound receptors. Thus, the design of GRP-R ligands has to be based on the structure of its natural ligands, BN and GRP. We recently mapped the BN binding epitope by NMR and here we exploited the same spectroscopy, combined with MD, to define BN conformation in proximity of biological membranes, where the interaction with GRP-R takes place. The gained structural information was used to identify a rigid C-galactosidic scaffold able to support pharmacophore groups mimicking the BN key residues' side chains in a suitable manner for binding to GRP-R. Our BN antagonists represent hit compounds for the rational design and synthesis of new ligands and modulators of GRP-R. The further optimization of the pharmacophore groups will allow to increase the biological activity. Due to their favorable chemical properties and stability, they could be employed for the active receptor-mediated targeting of GRP-R positive tumors.
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Affiliation(s)
- Alessandro Palmioli
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, P.zza della Scienza 2, 20126 Milan, Italy; Milan Center for Neuroscience, University of Milano-Bicocca, P.zza dell'Ateneo Nuovo 1, 20126 Milano, Italy
| | - Gabriella Nicolini
- Milan Center for Neuroscience, University of Milano-Bicocca, P.zza dell'Ateneo Nuovo 1, 20126 Milano, Italy; School of Medicine and Surgery, Experimental Neurology Unit, University of Milano - Bicocca, Via Cadore 48, 20900 Monza, MB, Italy
| | - Farida Tripodi
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, P.zza della Scienza 2, 20126 Milan, Italy
| | - Alexandre Orsato
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, P.zza della Scienza 2, 20126 Milan, Italy; Departamento de Química, CCE, Universidade Estadual de Londrina, CEP 86057-970 Londrina, Paraná, Brazil
| | - Cecilia Ceresa
- Milan Center for Neuroscience, University of Milano-Bicocca, P.zza dell'Ateneo Nuovo 1, 20126 Milano, Italy; School of Medicine and Surgery, Experimental Neurology Unit, University of Milano - Bicocca, Via Cadore 48, 20900 Monza, MB, Italy
| | - Elisabetta Donzelli
- Milan Center for Neuroscience, University of Milano-Bicocca, P.zza dell'Ateneo Nuovo 1, 20126 Milano, Italy; School of Medicine and Surgery, Experimental Neurology Unit, University of Milano - Bicocca, Via Cadore 48, 20900 Monza, MB, Italy
| | - Martina Arici
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, P.zza della Scienza 2, 20126 Milan, Italy
| | - Paola Coccetti
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, P.zza della Scienza 2, 20126 Milan, Italy
| | - Marcella Rocchetti
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, P.zza della Scienza 2, 20126 Milan, Italy
| | - Barbara La Ferla
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, P.zza della Scienza 2, 20126 Milan, Italy.
| | - Cristina Airoldi
- Department of Biotechnology and Biosciences, University of Milano - Bicocca, P.zza della Scienza 2, 20126 Milan, Italy; Milan Center for Neuroscience, University of Milano-Bicocca, P.zza dell'Ateneo Nuovo 1, 20126 Milano, Italy.
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3
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Abouzayed A, Tano H, Nagy Á, Rinne SS, Wadeea F, Kumar S, Westerlund K, Tolmachev V, Eriksson Karlström A, Orlova A. Preclinical Evaluation of the GRPR-Targeting Antagonist RM26 Conjugated to the Albumin-Binding Domain for GRPR-Targeting Therapy of Cancer. Pharmaceutics 2020; 12:E977. [PMID: 33081166 PMCID: PMC7594083 DOI: 10.3390/pharmaceutics12100977] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2020] [Revised: 10/12/2020] [Accepted: 10/14/2020] [Indexed: 01/02/2023] Open
Abstract
The targeting of gastrin-releasing peptide receptors (GRPR) was recently proposed for targeted therapy, e.g., radiotherapy. Multiple and frequent injections of peptide-based therapeutic agents would be required due to rapid blood clearance. By conjugation of the GRPR antagonist RM26 (D-Phe-Gln-Trp-Ala-Val-Gly-His-Sta-Leu-NH2) to an ABD (albumin-binding domain), we aimed to extend the blood circulation of peptides. The synthesized conjugate DOTA-ABD-RM26 was labelled with indium-111 and evaluated in vitro and in vivo. The labelled conjugate was stable in PBS and retained specificity and its antagonistic function against GRPR. The half-maximal inhibitory concentration (IC50) of natIn-DOTA-ABD-RM26 in the presence of human serum albumin was 49 ± 5 nM. [111In]In-DOTA-ABD-RM26 had a significantly longer residence time in blood and in tumors (without a significant decrease of up to 144 h pi) than the parental RM26 peptide. We conclude that the ABD-RM26 conjugate can be used for GRPR-targeted therapy and delivery of cytotoxic drugs. However, the undesirable elevated activity uptake in kidneys abolishes its use for radionuclide therapy. This proof-of-principle study justified further optimization of the molecular design of the ABD-RM26 conjugate.
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Affiliation(s)
- Ayman Abouzayed
- Department of Medicinal Chemistry, Uppsala University, 751 83 Uppsala, Sweden; (A.A.); (S.S.R.); (F.W.)
| | - Hanna Tano
- Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm, Sweden; (H.T.); (Á.N.); (S.K.); (K.W.); (A.E.K.)
| | - Ábel Nagy
- Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm, Sweden; (H.T.); (Á.N.); (S.K.); (K.W.); (A.E.K.)
| | - Sara S. Rinne
- Department of Medicinal Chemistry, Uppsala University, 751 83 Uppsala, Sweden; (A.A.); (S.S.R.); (F.W.)
| | - Fadya Wadeea
- Department of Medicinal Chemistry, Uppsala University, 751 83 Uppsala, Sweden; (A.A.); (S.S.R.); (F.W.)
| | - Sharmishtaa Kumar
- Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm, Sweden; (H.T.); (Á.N.); (S.K.); (K.W.); (A.E.K.)
| | - Kristina Westerlund
- Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm, Sweden; (H.T.); (Á.N.); (S.K.); (K.W.); (A.E.K.)
| | - Vladimir Tolmachev
- Department of Immunology, Genetics and Pathology, Uppsala University, 751 85 Uppsala, Sweden;
- Research Centrum for Oncotheranostics, Research School of Chemistry and Applied Biomedical Sciences, Tomsk Polytechnic University, Tomsk 634050, Russia
| | - Amelie Eriksson Karlström
- Department of Protein Science, School of Engineering Sciences in Chemistry, Biotechnology and Health, KTH Royal Institute of Technology, AlbaNova University Center, 106 91 Stockholm, Sweden; (H.T.); (Á.N.); (S.K.); (K.W.); (A.E.K.)
| | - Anna Orlova
- Department of Medicinal Chemistry, Uppsala University, 751 83 Uppsala, Sweden; (A.A.); (S.S.R.); (F.W.)
- Research Centrum for Oncotheranostics, Research School of Chemistry and Applied Biomedical Sciences, Tomsk Polytechnic University, Tomsk 634050, Russia
- Science for Life Laboratory, Uppsala University, 751 05 Uppsala, Sweden
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4
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On-cell saturation transfer difference NMR study of Bombesin binding to GRP receptor. Bioorg Chem 2020; 99:103861. [PMID: 32339813 DOI: 10.1016/j.bioorg.2020.103861] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Revised: 04/15/2020] [Accepted: 04/16/2020] [Indexed: 01/15/2023]
Abstract
We report the NMR characterization of the molecular interaction between Gastrin Releasing Peptide Receptor (GRP-R) and its natural ligand bombesin (BN). GRP-R is a transmembrane G-protein coupled receptor promoting the stimulation of cancer cell proliferation; in addition, being overexpressed on the surface of different human cancer cell lines, it is ideal for the development of new strategies for the selective targeted delivery of anticancer drugs and diagnostic devices to tumor cells. However, the design of new GRP-R binders requires structural information on receptor interaction with its natural ligands. The experimental protocol presented herein, based on on-cell STD NMR techniques, is a powerful tool for the screening and the epitope mapping of GRP-R ligands aimed at the development of new anticancer and diagnostic tools. Notably, the study can be carried out in a physiological environment, at the surface of tumoral cells overespressing GRP-R. Moreover, to the best of our knowledge, this is the first example of an NMR experiment able to detect and investigate the structural determinants of BN/GRP-R interaction.
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5
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Assessment of the conformational profile of bombesin by computational methods. J Mol Graph Model 2020; 98:107590. [PMID: 32234677 DOI: 10.1016/j.jmgm.2020.107590] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Revised: 03/17/2020] [Accepted: 03/18/2020] [Indexed: 12/27/2022]
Abstract
In the present work, the results of a computational study aimed at assessing the conformational profile of bombesin are reported. The conformational space of the peptide was sampled by means of a 4 μs accelerated molecular dynamics simulation in water, using an explicit solvent model. The results were analyzed using Principal Component Analysis to get essential information on peptide fluctuations, along with cluster analysis to characterize different conformations in the sample. Analysis of the results suggests that the peptide adopts helical structures at the C-terminus that tend to unwind at the end of the peptide chain, since there are many structures exhibiting only two turns of a helix at the central segment of the peptide. In addition, the peptide also adopts hairpin turn structures at the N-terminus. Results of the simulation were confronted with available NMR results in a 2,2,2-trifluoroethanol/water (30% v/v) solution. Distances deduced form NOEs experiments only provide support to the presence of helical conformations that represent the most populated structures in the simulation. The absence of other conformations in the NMR experiments can be explained to be due to the α-helix enhancing nature of the solvent used in the experiments.
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6
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Sharma P, Singh P, Bisetty K, Corcho FJ, Perez JJ. Conformational profile of bombesin assessed using different computational protocols. J Mol Graph Model 2010; 29:581-90. [PMID: 21144782 DOI: 10.1016/j.jmgm.2010.11.006] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2010] [Revised: 10/28/2010] [Accepted: 11/09/2010] [Indexed: 10/18/2022]
Abstract
The present work involves the study of the conformational profile of bombesin using different computational procedures used to explore the configurational space based on molecular dynamics simulations. Specifically, the present study describes the effect of using Berendsen's versus Langevin's thermostat and on the other hand, the use of the multicanonical replica exchange molecular dynamics as compared to standard molecular dynamics. In these simulations the solvent was modeled using the Onufriev, Bashford and Case implementation of Generalized Born procedure. The detailed computational analysis agrees well with the aggregated information previously reported in the NMR study of the peptide in a mixture of trifluoroethanol/water. Present results show a clear preference for the peptide to attain a helical structure on the segment 6-14, with a tendency to adopt a α-helix at the C-terminus aligning the aromatic residues Trp8 and His12 together with Gln7, known to be important for peptide mediated activation. Finally, the three methodologies used in the present work yield similar structural results, although a detailed analysis reveals biases that need to be considered when performing this kind of studies.
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Affiliation(s)
- Parul Sharma
- Department of Chemistry, Durban University of Technology, Steve Biko Campus, P.O. Box 1334, Durban 4000, South Africa
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7
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Díaz MD, Fioroni M, Burger K, Berger S. Evidence of complete hydrophobic coating of bombesin by trifluoroethanol in aqueous solution: an NMR spectroscopic and molecular dynamics study. Chemistry 2002; 8:1663-9. [PMID: 11933094 DOI: 10.1002/1521-3765(20020402)8:7<1663::aid-chem1663>3.0.co;2-p] [Citation(s) in RCA: 63] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Bombesin is a tetradecapeptide that possesses a random coil structure in pure water. In the presence of 30 % (v/v) 2,2,2-trifluoroethanol (TFE), it adopts a partial helical conformation involving the C-terminal amino acids 6-14. This conformational change, known as the TFE effect, is studied here in terms of the solvation state of the peptide at different TFE concentrations by means of intermolecular homo- and heteronuclear NOE measurements. When an aqueous solution of bombesin is titrated with TFE, a continual decrease in the water/peptide interactions and a concomitant increase in the TFE/peptide interactions is observed, and at 30 % (v/v) TFE no homonuclear NOEs between water and the peptide can be detected. The conformational transition of the bombesin molecule is thus accompanied by a complete surface covering with TFE. A parallel molecular dynamics (MD) study of the peptide in aqueous solution with the single-point charge (SPC) water model and in a 30 % (v/v) TFE/water mixture with a recently developed TFE model has also been performed. The 10 ns simulations were in agreement with the experimental data. The calculations indicate stabilisation of the alpha-helix in the H(2)O/TFE mixture, in contrast to the situation in pure water, and clustering of the TFE molecules around the peptide.
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Affiliation(s)
- M Dolores Díaz
- Institut für Analytische Chemie, Universität Leipzig Linnéstrasse 3, 04103 Leipzig, Germany
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8
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Yarovsky I, Hearn MTW, Aguilar MI. Molecular Simulation of Peptide Interactions with an RP-HPLC Sorbent. J Phys Chem B 1997. [DOI: 10.1021/jp972232z] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- I. Yarovsky
- Department of Biochemistry & Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3168, Australia
| | - M. T. W. Hearn
- Department of Biochemistry & Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3168, Australia
| | - M. I. Aguilar
- Department of Biochemistry & Molecular Biology, Monash University, Wellington Road, Clayton, Victoria 3168, Australia
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9
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Gasmi G, Singer A, Forman-Kay J, Sarkar B. NMR structure of neuromedin C, a neurotransmitter with an amino terminal CuII-, NiII-binding (ATCUN) motif. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 1997; 49:500-9. [PMID: 9266477 DOI: 10.1111/j.1399-3011.1997.tb01157.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The structure of neuromedin C, a 10-residue bombesin-like neuropeptide with the sequence Gly-Asn-His-Trp-Ala-Val-Gly-His-Leu-Met-NH2, has been investigated. Like human serum albumin, neuromedin C contains the amino-terminal CuII-, NiII-binding (ATCUN) motif which has high affinity for CuII and NiII. The solution structure of the NiII-peptide complex has been calculated based on 2D ROESY data obtained at 25 degrees C, using a hybrid distance geometry-simulated annealing approach. Comparison of 1H, 13C and 15N chemical shifts and ROESY data in the presence and absence of NiII demonstrates that the metal binds at the N-terminus of the peptide, leading to a conformational change. The metal complex adopts a conformation comprising two connected turns including residues 1Gly to 3His and 5Ala to 8His. The first turn corresponds to the NiII coordination ligands in a square planar conformation, and the second reflects the interaction between 4Trp and 8His. The results may have important physiological implications in the phenomenon of neurotransmission.
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Affiliation(s)
- G Gasmi
- Department of Biochemistry Research, Hospital for Sick Children, Toronto, Ontario, Canada
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10
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Cavatorta P, Favilla R, Mazzini A, Franzoni L, Spisni A, Szabo AG. Fluorescence studies on the conformation of litorin in solution and in the presence of model membranes. J Fluoresc 1993; 3:211-4. [DOI: 10.1007/bf00865263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/1993] [Indexed: 12/01/2022]
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11
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Chaturvedi S, Parthasarathy R. Synthesis and immunological properties of bombesin analogs. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1993; 41:333-7. [PMID: 8496014 DOI: 10.1111/j.1399-3011.1993.tb00448.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Bombesin (Bn, pGlu-Gln-Arg-Leu-Gly-Asn-Gln-Trp-Ala-Val-Gly-His-Leu-Met-NH2) is one of the most potent peptides, possessing a variety of physiological and pharmacological functions. We find from CD spectroscopy that the eight C-terminal residues of bombesin [Bn(7-14)NH2] have an ordered structure, and replacement of His-12 with Pro of Bn(7-14)NH2 changes the conformation from ordered to a more unordered form. Antibodies to Bn(7-14)NH2 cross-react to Bn and gastrin releasing peptide (GRP) in a dose-dependent manner. Antibodies to the Pro-analog do not recognize Bn or GRP. Substitution of the C-terminal amide by isopropylamide [Bn(7-14)NHC3H7(i)] makes its antibodies more specific to Bn than to GRP. It appears that this region of the peptide is an important antigenic determinant, which makes these antibodies differentiate between BN and GRP.
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Affiliation(s)
- S Chaturvedi
- Center for Crystallographic Research, Roswell Park Cancer Institute, Buffalo, New York
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12
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Purcell AW, Aguilar MI, Hearn MT. High-performance liquid chromatography of amino acids, peptides and proteins. CXV. Thermodynamic behaviour of peptides in reversed-phase chromatography. J Chromatogr A 1992; 593:103-17. [PMID: 1639893 DOI: 10.1016/0021-9673(92)80274-x] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The thermodynamic behaviour of three peptides, bombesin, beta-endorphin and glucagon, was studied under reversed-phase high-performance liquid chromatographic conditions. Experimental data related to the interactive surface contact area (S values) and solute affinity (log k0) were derived over a range of temperatures between 5 and 85 degrees C. These experimental conditions allowed changes in the secondary structure of the solute to be monitored. The influence of the nature of the stationary phase ligand on the relative conformational stability of the three peptides was analysed by acquiring data with n-octadecyl silica (C18) and n-butyl silica (C4) sorbents. Values for the relative changes in entropy and enthalpy associated with the interactive process were also determined. The results provide further insight into the factors involved with the stabilization of secondary structure and the mechanism of the interaction of peptides with hydrophobic surfaces.
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Affiliation(s)
- A W Purcell
- Department of Biochemistry, Monash University, Clayton, Victoria, Australia
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13
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Di Bello C, Scatturin A, Vertuani G, D'Auria G, Gargiulo M, Paolillo L, Trivellone E, Gozzini L, De Castiglione R. Conformational studies on bombesin antagonists: CD and NMR characterization of [Thr6, Leu13 psi(CH2NH) Met14] bombesin (6-14). Biopolymers 1991; 31:1397-408. [PMID: 1816876 DOI: 10.1002/bip.360311206] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The conformational flexibility of the [Thr6, Leu13 psi(CH2NH) Met14] bombesin (6-14) nonapeptide has been studied by CD and one- and two-dimensional (1D and 2D) nmr techniques. The CD and nmr parameters in different solvents and in a micellar environment (SDS) are compared with the data collected for the parent bombesin (BN) and [D-Phe12, Leu14]BN. A preliminary investigation on spantide is also reported. In particular, the results obtained from CD measurements indicate that there is a shift from random coil structures, in aqueous solutions, toward folded structures in apolar media (2,2,2-trifluoroethanol) and in a membrane-mimetic environment (40 mM SDS) for all three peptides, namely BN, [D-Phe12, Leu14]BN, and [Thr6, Leu13 psi(CH2NH) Met14]BN (6-14). Spantide, which also possesses some inhibitory activity against BN but very little sequence similarity, even in water, shows an ordered conformation. Nuclear magnetic resonance parameters such as backbone NH-alpha CH coupling constant values, amidic temperature coefficients, and the presence of only sequential nuclear Overhauser effects have not provided, so far, any clear evidence for a preferential ordered structure in the peptides studied, and this may be due to rapid exchange among different conformers in the nmr time scale.
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Affiliation(s)
- C Di Bello
- Institute of Industrial Chemistry, University of Padova, Italy
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14
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de Kroon AI, de Gier J, de Kruijff B. The effect of a membrane potential on the interaction of mastoparan X, a mitochondrial presequence, and several regulatory peptides with phospholipid vesicles. BIOCHIMICA ET BIOPHYSICA ACTA 1991; 1068:111-24. [PMID: 1680397 DOI: 10.1016/0005-2736(91)90199-i] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Recently the pH gradient evoked by a K+ diffusion potential was shown to translocate a synthetic monobasic amphipathic hexapeptide across the bilayer of lipid vesicles (De Kroon, A.I.P.M., Vogt, B., Van 't Hof, R., De Kruijff, B. and De Gier, J. (1991) Biophys. J. 60, in press). Here this observation is extended by studying the effect of a membrane potential on a set of bioactive peptides. The panel of peptides comprises the toxin mastoparan X, a tryptophan-containing analogue of the presequence of the mitochondrial protein cytochrome oxidase subunit IV (preCoxIV(1-25)W18), and the regulatory peptides ACTH(1-24), alpha-MSH, ACTH(1-10), dynorphin A, bombesin, and LHRH. The interaction of these peptides with phospholipid vesicles has been measured using the intrinsic tryptophan residue as fluorescent probe. In the absence of a K+ diffusion potential only mastoparan X and the presequence show considerable binding to vesicles consisting of phosphatidylcholine (PC). In contrast, under these conditions all peptides display affinity for vesicles consisting of the acidic phospholipid cardiolipin (CL), the extent of which depends on the net positive charge of the peptide. Application of a K+ diffusion potential to large unilamellar vesicles (LUV) consisting of PC results in a time dependent tryptophan fluorescence increase for mastoparan X, which is accelerated upon incorporating increasing amounts of CL into the LUV. A similar fluorescence increase in response to a K+ diffusion potential was observed for the above model peptide. Yet the mechanism resulting in the fluorescence increase of mastoparan X is completely different from that of the hexapeptide. Binding experiments indicate that a membrane potential-induced enhanced binding of the peptide to the outer surface of the vesicles contributes to the fluorescence increase. PreCoxIV(1-25)W18, dynorphin A, and ACTH(1-24) show fluorescence responses upon applying a membrane potential that are consistent with that of mastoparan X, whereas the other peptides tested do not respond up to a LUV CL content of 50%. The results tentatively suggest that the membrane potential only affects a peptide when it has the ability to adopt a stable membrane bound conformation.
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Affiliation(s)
- A I de Kroon
- Centre for Biomembranes and Lipid Enzymology, University of Utrecht, The Netherlands
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15
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Di Bello C, Scatturin A, D'Auria G, Gargiulo M, Paolillo L, Trivellone E, De Castiglione R. Fluorescence, CD, and NMR studies on spantide, a bombesin and substance P antagonist. Biopolymers 1991; 31:643-52. [PMID: 1718471 DOI: 10.1002/bip.360310609] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The conformational properties of spantide [(D-Arg, D-Trp, Leu) substance P] have been studied by fluorescence, CD, and nmr techniques. The fluorescence, CD, and nmr parameters in different solvents and in a micellar environment (SDS) are compared with the data collected for bombesin. A preliminary investigation on [D-Pro] spantide is also reported.
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Affiliation(s)
- C Di Bello
- Institute of Industrial Chemistry, University of Padova, Italy
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16
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Cavatorta P, Sartor G, Neyroz P, Farruggia G, Franzoni L, Szabo AG, Spisni A. Fluorescence and CD studies on the conformation of the gastrin releasing peptide in solution and in the presence of model membranes. Biopolymers 1991; 31:653-61. [PMID: 1932564 DOI: 10.1002/bip.360310610] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The conformation of the heptacosapeptide hormone, gastrin releasing peptide, has been studied in buffer and in the presence of lipids, using static and dynamic fluorescence and CD. The results obtained show that, in buffer, the hormone exists in a collection of flexible, random coil type conformers, characterized by a beta-turn between residues 14-19. On the other hand, organic solvents can induce some degree of ordered secondary structure in the peptide chain. The marked changes, observed in CD and fluorescence spectra upon addition of lysolecitin micelles and dimyristoylphosphatidylserine vesicles, clearly show that the peptide interacts with lipids, assuming a lipid specific configuration. Interestingly, no significative spectroscopic changes are produced by exposure to dimyristoylphosphatidylcholine vesicles both in the gel and liquid-chrystalline phases, suggesting a requirement for negatively charged lipids during the process of hormone-membrane interaction.
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Affiliation(s)
- P Cavatorta
- Department of Physics Section of Biophysics, University of Parma, Italy
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17
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Naldini L, Cirillo D, Moody TW, Comoglio PM, Schlessinger J, Kris R. Solubilization of the receptor for the neuropeptide gastrin-releasing peptide (bombesin) with functional ligand binding properties. Biochemistry 1990; 29:5153-60. [PMID: 2165804 DOI: 10.1021/bi00473a022] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Abstract
The receptor for the neuropeptide gastrin-releasing peptide, the mammalian homologue of bombesin, was solubilized from rat brain and Swiss 3T3 cells by using the zwitterionic detergent 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonic acid (CHAPS) and the cholesteryl hemisuccinate ester (CHS). Only the combination of the detergent CHAPS and the cholesteryl ester CHS in a glycerol-containing buffer satisfactorily preserved the binding activity upon solubilization. Specific binding activity was only solubilized from cell lines and tissue preparations known to express the GRP receptor. The dissociation constant (Kd) for the receptor solubilized from rat brain and Swiss 3T3 cells was 0.6 nM, similar to the value of 0.8 nM calculated for the membrane-bound receptor. Binding was saturable and reached equilibrium after approximately 2 h at 4 degrees C. The identity of the solubilized receptor with the membrane-bound one was further confirmed by the concordance of the relative binding affinities of various established bombesin analogues.
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Affiliation(s)
- L Naldini
- Rorer Biotechnology, Inc., King of Prussia, Pennsylvania 19406
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18
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Carver JA, Collins JG. NMR identification of a partial helical conformation for bombesin in solution. EUROPEAN JOURNAL OF BIOCHEMISTRY 1990; 187:645-50. [PMID: 2303058 DOI: 10.1111/j.1432-1033.1990.tb15348.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The conformation of bombesin in trifluoroethanol/water mixtures has been studied using 1H-NMR spectroscopy. By a combination of two-dimensional 1H-NMR techniques and measurement of vicinal NH-alpha-CH spin-spin coupling constants, the secondary structure of the molecule has been determined. Bombesin adopts a helical structure in the region from Asn-6 to Met-14 with the remaining N-terminal portion existing as a more extended structure. The structure is very similar to that proposed from Fourier-transform infrared spectroscopic measurements for bombesin inserted into lipid bilayers [D. Erne & R. Schwyzer (1987) Biochemistry 26, 6316-6319]. The absence of a hydrogen bond between the sidechains of Trp-8 and His-12 is discussed in terms of the ionization state of His-12. Stabilisation of the helix results when His-12 is in the ionized state.
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Affiliation(s)
- J A Carver
- Department of Chemistry, University of Wollongong, Australia
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19
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Yamashita S, Szabo AG, Krajcarski DT, Yamasaki N. Fluorescence Studies on the Phase Dependence of Interactions between a Tripeptide, Lys–Trp–Lys, and Dimyristoylphosphatidylserine. BULLETIN OF THE CHEMICAL SOCIETY OF JAPAN 1989. [DOI: 10.1246/bcsj.62.3075] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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20
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Di Bello C, Scanelli A, Corradini MG, Paolillo L, Trivellone E, Scatturin A, Vertuani G, Gozzini L, de Castiglione R. Conformation studies on bombesin receptor antagonists: 500 MHz NMR and CD characterization of synthetic (D-Phe12, Leu14)-bombesin. Biochem Biophys Res Commun 1989; 161:987-93. [PMID: 2545203 DOI: 10.1016/0006-291x(89)91340-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The conformation flexibility of the tetradecapeptide hormone bombesin and its synthetic antagonist (DPhe12, Leu14)-bombesin has been studied using nuclear magnetic resonance and circular dichroism techniques. The spectral features observed indicate that the ordered structure present in the C-terminal pentapeptide moiety of native BBS is lost in the (DPhe12, Leu14) analog.
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Affiliation(s)
- C Di Bello
- Institute of Industrial Chemistry, University of Padova, Italy
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21
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Cavatorta P, Spisni A, Szabo AG, Farruggia G, Franzoni L, Masotti L. Conformation of bombesin in buffer and in the presence of lysolecithin micelles: NMR, CD, and fluorescence studies. Biopolymers 1989; 28:441-63. [PMID: 2720119 DOI: 10.1002/bip.360280140] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
The conformation of the tetradecapeptide hormone bombesin has been studied in buffer and in the presence of lysolecithin micelles, using static and dynamic fluorescence, CD, and one- and two-dimensional nmr. The results obtained show that in buffer bombesin is present in an extended flexible chain, with no evidence for any ordered secondary structure. A marked change in the CD spectrum is observed changing from buffer to the lipid suspension. Concomitantly, the 1H-nmr spectrum of bombesin, in a D2O lipid dispersion, shows the persistence of resonances due to exchangeable protons and in similar conditions the fluorescence intensity increases. We think therefore that these results strongly support the hypothesis that bombesin interacts with the lipid phase, assuming ordered secondary structure. Finally, the marked dependence of tryptophan fluorescence quantum efficiency and order parameter from the hormone concentration in the presence of lysolecithin but not in buffer leads to the conclusion that bombesin can associate into the lipid matrix.
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22
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Negri L, Improta G, Broccardo M, Melchiorri P. Phyllolitorins: a new family of bombesin-like peptides. Ann N Y Acad Sci 1988; 547:415-28. [PMID: 3239894 DOI: 10.1111/j.1749-6632.1988.tb23907.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- L Negri
- Institute of Medical Pharmacology, University "La Sapienza, Rome, Italy
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23
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Schwyzer R. Estimated membrane structure and receptor subtype selection of an opioid alkaloid-peptide hybrid. INTERNATIONAL JOURNAL OF PEPTIDE AND PROTEIN RESEARCH 1988; 32:476-83. [PMID: 2907750 DOI: 10.1111/j.1399-3011.1988.tb01378.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Preferred conformation, orientation, and accumulation of dynorphin A-(1-8)-octapeptide, naltrexone, and N beta-(D-Leu-D-Arg-D-Arg-D-Leu-D-Phe)-naltrexamine (Lipkowsky et al., 1988) were estimated according to established procedures. Opioid binding site affinities and selectivities available from the literature were correlated with the estimated parameters of lipid membrane interaction. The results agreed with the molecular mechanism of opioid receptor subtype selection proposed earlier.
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Affiliation(s)
- R Schwyzer
- Department of Molecular Biology and Biophysics, Swiss Federal Institute of Technology (ETH), Zürich
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24
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Erne D, Schwyzer R. Membrane structure of bombesin studied by infrared spectroscopy. Prediction of membrane interactions of gastrin-releasing peptide, neuromedin B, and neuromedin C. Biochemistry 1987; 26:6316-9. [PMID: 3427006 DOI: 10.1021/bi00394a004] [Citation(s) in RCA: 60] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Bombesin, in contact with flat phospholipid bilayer membranes, was shown to adopt a membrane structure similar to that of substance P, dynorphin-(1-13)-tridecapeptide, and adrenocorticotropin-(1-24)-tetracosapeptide. The C-terminal message segment, comprising 8-10 amino acid residues, is inserted into a relatively hydrophobic membrane compartment as an alpha-helical domain oriented perpendicularly on the membrane surface. The N-terminal, hydrophilic tetrapeptide segment remains in the aqueous compartment as a random coil. This was shown with IR and IR attenuated total reflection spectroscopy. Equilibrium thermodynamic estimations confirmed the observed membrane structure with respect to helix length, strength of hydrophobic membrane association, and orientation (caused by favorably oriented molecular amphiphilic and helix electric dipole moments). The membrane structure may explain why Trp-8 and His-12 are essential for biologic activity. Neuromedin B is predicted to be able to adopt a membrane structure similar to that of bombesin. However, gastrin-releasing peptide and neuromedin C are predicted not to behave in the same manner. The molecular mechanism of receptor subtype selection by bombesin-like peptides may prove to be similar to that observed earlier for opioid peptides and the neurokinins.
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Affiliation(s)
- D Erne
- Department of Molecular Biology and Biophysics, Swiss Federal Institute of Technology (ETH), Zürich
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25
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Carver JA. The conformation of bombesin in solution as determined by two-dimensional 1H-NMR techniques. EUROPEAN JOURNAL OF BIOCHEMISTRY 1987; 168:193-9. [PMID: 3665915 DOI: 10.1111/j.1432-1033.1987.tb13404.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The 1H nuclear magnetic resonance spectrum of the tetradecapeptide, bombesin, has been assigned in (2H6)dimethyl sulphoxide solution and aqueous solution using two-dimensional techniques. The chemical shifts in both solvents indicate that the molecule has little secondary structure and adopts a random coil conformation. A comparison is made between the spectra of various smaller bombesin fragments and the intact polypeptide.
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Affiliation(s)
- J A Carver
- Department of Biochemistry, University of Adelaide, South Australia
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