1
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Lamarche J, Alcoceba Álvarez E, Cordeau E, Enjalbal C, Massai L, Messori L, Lobinski R, Ronga L. Comparative reactivity of medicinal gold(I) compounds with the cyclic peptide vasopressin and its diselenide analogue. Dalton Trans 2021; 50:17487-17490. [PMID: 34796892 DOI: 10.1039/d1dt03470g] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The reactions of the medicinal gold(I) compound auranofin and its close analogues with vasopressin and the diselenide analogue were comparatively investigated by LC-electrospray MS/MS. Evidence is gained of the possible cleavage of the S-S and Se-Se bridges induced by Au(I). Notably, we found that, in the absence of reducing agents, the sulfur and selenium atoms are metallated only at high temperature (70 °C) with the preferential binding of gold to selenium. The reaction with the S-S bridge can take place at physiological temperature (37 °C) under reducing conditions. The implications of these results are discussed in the general frame of the reactivity of biologically relevant soft Lewis acids with peptides and proteins.
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Affiliation(s)
- Jeremy Lamarche
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France.
| | | | | | | | - Lara Massai
- Department of Chemistry, University of Florence, Via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy
| | - Luigi Messori
- Department of Chemistry, University of Florence, Via della Lastruccia 3-13, 50019 Sesto Fiorentino, Italy
| | - Ryszard Lobinski
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France. .,IM Sechenov First Moscow State Medical University (Sechenov University), 119435 Moscow, Russia
| | - Luisa Ronga
- Université de Pau et des Pays de l'Adour, E2S UPPA, CNRS, IPREM, Pau, France.
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2
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Che K, Muttenthaler M, Kurzbach D. Conformational selection of vasopressin upon V 1a receptor binding. Comput Struct Biotechnol J 2021; 19:5826-5833. [PMID: 34765097 PMCID: PMC8567363 DOI: 10.1016/j.csbj.2021.10.024] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 10/14/2021] [Accepted: 10/14/2021] [Indexed: 11/30/2022] Open
Abstract
The neuropeptide vasopressin (VP) and its three G protein-coupled receptors (V1aR, V1bR and V2R) are of high interest in a wide array of drug discovery programs. V1aR is of particular importance due to its cardiovascular functions and diverse roles in the central nervous system. The structure–activity relationships underpinning ligand-receptor interactions remain however largely unclear, hindering rational drug design. This is not least due to the high structural flexibility of VP in its free as well as receptor-bound states. In this work, we developed a novel approach to reveal features of conformational selectivity upon VP-V1aR complex formation. We employed virtual screening strategies to probe VP’s conformational space for transiently adopted structures that favor binding to V1aR. To this end, we dissected the VP conformational space into three sub-ensembles, each containing distinct structural sets for VP’s three-residue C-terminal tail. We validated the computational results with experimental nuclear magnetic resonance (NMR) data and docked each sub-ensemble to V1aR. We observed that the conformation of VP’s three-residue tail significantly modulated the complex dissociation constants. Solvent-exposed and proline trans-configured VP tail conformations bound to the receptor with three-fold enhanced affinities compared to compacted or cis-configured conformations. The solvent-exposed and more flexible structures facilitated unique interaction patterns between VP and V1aR transmembrane helices 3, 4, and 6 which led to high binding energies. The presented “virtual conformational space screening” approach, integrated with NMR spectroscopy, thus enabled identification and characterization of a conformational selection-type complex formation mechanism that confers novel perspectives on targeting the VP-V1aR interactions at the level of the encounter complex – an aspect that opens novel research avenues for understanding the functionality of the evolutionary selected conformational properties of VP, as well as guidance for ligand design strategies to provide more potent and selective VP analogues.
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Affiliation(s)
- Kateryna Che
- University Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Währinger Str. 38, A-1090 Vienna, Austria
| | - Markus Muttenthaler
- University Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Währinger Str. 38, A-1090 Vienna, Austria
- The University of Queensland, Institute for Molecular Bioscience, 306 Carmody Rd, 4072 St Lucia, Brisbane, Queensland, Australia
| | - Dennis Kurzbach
- University Vienna, Faculty of Chemistry, Institute of Biological Chemistry, Währinger Str. 38, A-1090 Vienna, Austria
- Corresponding author.
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3
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Damjanovic J, Miao J, Huang H, Lin YS. Elucidating Solution Structures of Cyclic Peptides Using Molecular Dynamics Simulations. Chem Rev 2021; 121:2292-2324. [PMID: 33426882 DOI: 10.1021/acs.chemrev.0c01087] [Citation(s) in RCA: 40] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Protein-protein interactions are vital to biological processes, but the shape and size of their interfaces make them hard to target using small molecules. Cyclic peptides have shown promise as protein-protein interaction modulators, as they can bind protein surfaces with high affinity and specificity. Dozens of cyclic peptides are already FDA approved, and many more are in various stages of development as immunosuppressants, antibiotics, antivirals, or anticancer drugs. However, most cyclic peptide drugs so far have been natural products or derivatives thereof, with de novo design having proven challenging. A key obstacle is structural characterization: cyclic peptides frequently adopt multiple conformations in solution, which are difficult to resolve using techniques like NMR spectroscopy. The lack of solution structural information prevents a thorough understanding of cyclic peptides' sequence-structure-function relationship. Here we review recent development and application of molecular dynamics simulations with enhanced sampling to studying the solution structures of cyclic peptides. We describe novel computational methods capable of sampling cyclic peptides' conformational space and provide examples of computational studies that relate peptides' sequence and structure to biological activity. We demonstrate that molecular dynamics simulations have grown from an explanatory technique to a full-fledged tool for systematic studies at the forefront of cyclic peptide therapeutic design.
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Affiliation(s)
- Jovan Damjanovic
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - Jiayuan Miao
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - He Huang
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
| | - Yu-Shan Lin
- Department of Chemistry, Tufts University, Medford, Massachusetts 02155, United States
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4
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Röder K, Wales DJ. Mutational Basin-Hopping: Combined Structure and Sequence Optimization for Biomolecules. J Phys Chem Lett 2018; 9:6169-6173. [PMID: 30299103 DOI: 10.1021/acs.jpclett.8b02839] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The study of energy landscapes has led to a good understanding of how and why proteins and nucleic acids adopt their native structure. Through evolution, sequences have adapted until they exhibit a strongly funneled energy landscape, stabilizing the native fold. Design of artificial biomolecules faces the challenge of creating similar stable, minimally frustrated, and functional sequences. Here we present a biminimization approach, mutational basin-hopping, in which we simultaneously use global optimization to optimize the energy and a target function describing a desired property of the system. This optimization of structure and sequence is a generalized basin-hopping method and produces an efficient design process, which can target properties such as binding affinity or solubility.
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Affiliation(s)
- Konstantin Röder
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , U.K
| | - David J Wales
- Department of Chemistry , University of Cambridge , Lensfield Road , Cambridge CB2 1EW , U.K
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5
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Haensele E, Mele N, Miljak M, Read CM, Whitley DC, Banting L, Delépée C, Sopkova-de Oliveira Santos J, Lepailleur A, Bureau R, Essex JW, Clark T. Conformation and Dynamics of Human Urotensin II and Urotensin Related Peptide in Aqueous Solution. J Chem Inf Model 2017; 57:298-310. [DOI: 10.1021/acs.jcim.6b00706] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
| | - Nawel Mele
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - Marija Miljak
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | | | | | | | - Carla Delépée
- Normandie
Université, CS 14032 Caen Cedex 5, France, Centre d’Etudes
et de Recherche sur le Médicament de Normandie (CERMN, EA 4258,
FR CNRS 3038 INC3M SF 4206 ICORE), UFR des Sciences Pharmaceutiques, Université de Caen Basse−Normandie (UNICAEN), F-14032 Caen, France
| | - Jana Sopkova-de Oliveira Santos
- Normandie
Université, CS 14032 Caen Cedex 5, France, Centre d’Etudes
et de Recherche sur le Médicament de Normandie (CERMN, EA 4258,
FR CNRS 3038 INC3M SF 4206 ICORE), UFR des Sciences Pharmaceutiques, Université de Caen Basse−Normandie (UNICAEN), F-14032 Caen, France
| | - Alban Lepailleur
- Normandie
Université, CS 14032 Caen Cedex 5, France, Centre d’Etudes
et de Recherche sur le Médicament de Normandie (CERMN, EA 4258,
FR CNRS 3038 INC3M SF 4206 ICORE), UFR des Sciences Pharmaceutiques, Université de Caen Basse−Normandie (UNICAEN), F-14032 Caen, France
| | - Ronan Bureau
- Normandie
Université, CS 14032 Caen Cedex 5, France, Centre d’Etudes
et de Recherche sur le Médicament de Normandie (CERMN, EA 4258,
FR CNRS 3038 INC3M SF 4206 ICORE), UFR des Sciences Pharmaceutiques, Université de Caen Basse−Normandie (UNICAEN), F-14032 Caen, France
| | - Jonathan W. Essex
- School
of Chemistry, University of Southampton, Highfield, Southampton SO17 1BJ, United Kingdom
| | - Timothy Clark
- Computer-Chemie-Centrum
and Interdisciplinary Center for Molecular Materials, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstraße 25, 91052 Erlangen, Germany
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6
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Haensele E, Saleh N, Read CM, Banting L, Whitley DC, Clark T. Can Simulations and Modeling Decipher NMR Data for Conformational Equilibria? Arginine–Vasopressin. J Chem Inf Model 2016; 56:1798-807. [PMID: 27585313 DOI: 10.1021/acs.jcim.6b00344] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Elke Haensele
- Computer-Chemie-Centrum, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstraße 25, 91052 Erlangen, Germany
| | - Noureldin Saleh
- Computer-Chemie-Centrum, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstraße 25, 91052 Erlangen, Germany
| | | | | | | | - Timothy Clark
- Computer-Chemie-Centrum, Friedrich-Alexander-Universität Erlangen-Nürnberg, Nägelsbachstraße 25, 91052 Erlangen, Germany
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7
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Lubecka EA, Sikorska E, Sobolewski D, Prahl A, Slaninová J, Ciarkowski J. Potent antidiuretic agonists, deamino-vasopressin and desmopressin, and their inverso analogs: NMR structure and interactions with micellar and liposomic models of cell membrane. Biopolymers 2016; 106:245-59. [PMID: 26916937 DOI: 10.1002/bip.22825] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2015] [Revised: 02/11/2016] [Accepted: 02/13/2016] [Indexed: 11/08/2022]
Abstract
Deamination of vasopressin (AVP) enhances its antidiuretic activity. Moreover, introduction of D-Arg8 instead of its L enantiomer in deamino-vasopressin (dAVP) results in an extremely potent and selective antidiuretic agonist - desmopressin (dDAVP). In this study we describe the synthesis, pharmacological properties and structures of these two potent antidiuretic agonists, and their inverso analogs. The structures of the peptides are studied in micellar and liposomic models of cell membrane using CD spectroscopy. Additionally, three-dimensional structures in mixed anionic-zwitterionic micelles are obtained using NMR spectroscopy supported by molecular dynamics simulations. Our conformational studies have shown that desmopressin in a membrane mimicking environment adopts one of the characteristic for vasopressin-like peptides β-turn - in position 3,4. Furthermore, dDAVP shows the tendency to create a β-turn in the Cys6-Gly9 C-tail, considered to be important for the antidiuretic activity, and also some tendency to adopt a 5,6 β-turn. In desmopressin, in contrast to the native vasopressin, deamino-vasopressin and [D-Arg8]-vasopressin (DAVP), the Arg8 side chain, crucial for the pressor and antidiuretic activities, is very well exposed for interaction with the receptor, whereas Gly9, crucial for the pressor and uterotonic activities, is situated together with the C-terminal amide group very close to the tocin ring. The arrangements of the Gln4 and Asn5 side chains, being crucial for OT activity, also differ in desmopressin as compared to those of AVP, dAVP and DAVP. These differences in arrangement of the important for activities side chains are likely to explain extremely potent and selective antidiuretic activities of desmopressin. © 2016 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 106: 245-259, 2016.
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Affiliation(s)
- Emilia A Lubecka
- Faculty of Chemistry, University of Gdańsk, Gdańsk, 80-308, Poland
| | - Emilia Sikorska
- Faculty of Chemistry, University of Gdańsk, Gdańsk, 80-308, Poland
| | | | - Adam Prahl
- Faculty of Chemistry, University of Gdańsk, Gdańsk, 80-308, Poland
| | - Jiřina Slaninová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10 Prague, Czech Republic
| | - Jerzy Ciarkowski
- Faculty of Chemistry, University of Gdańsk, Gdańsk, 80-308, Poland
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8
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Lubecka EA, Sikorska E, Sobolewski D, Prahl A, Slaninová J, Ciarkowski J. Arginine-, D-arginine-vasopressin, and their inverso analogues in micellar and liposomic models of cell membrane: CD, NMR, and molecular dynamics studies. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 44:727-43. [PMID: 26290060 PMCID: PMC4628624 DOI: 10.1007/s00249-015-1071-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 07/22/2015] [Accepted: 08/03/2015] [Indexed: 01/21/2023]
Abstract
We describe the synthesis, pharmacological properties, and structures of antidiuretic agonists, arginine vasopressin (AVP) and [d-Arg8]-vasopressin (DAVP), and their inverso analogues. The structures of the peptides are studied based on micellar and liposomic models of cell membranes using CD spectroscopy. Additionally, three-dimensional structures in mixed anionic–zwitterionic micelles are obtained using NMR spectroscopy and molecular dynamics simulations. NMR data have shown that AVP and DAVP tend to adopt typical of vasopressin-like peptides β-turns: in the 2–5 and 3–6 fragments. The inverso-analogues also adopt β-turns in the 3–6 fragments. For this reason, their inactivity seems to be due to the difference in side chains orientations of Tyr2, Phe3, and Arg8, important for interactions with the receptors. Again, the potent antidiuretic activity of DAVP can be explained by CD data suggesting differences in mutual arrangement of the aromatic side chains of Tyr2 and Phe3 in this peptide in liposomes rather than of native AVP. In the presence of liposomes, the smallest conformational changes of the peptides are noticed with DPPC and the largest with DPPG liposomes. This suggests that electrostatic interactions are crucial for the peptide–membrane interactions. We obtained similar, probably active, conformations of the antidiuretic agonists in the mixed DPC/SDS micelles (5:1) and in the mixed DPPC/DPPG (7:3) liposomes. Thus it can be speculated that the anionic–zwitterionic liposomes as well as the anionic–zwitterionic micelles, mimicking the eukaryotic cell membrane environment, partially restrict conformational freedom of the peptides and probably induce conformations resembling those of biologically relevant ones.
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Affiliation(s)
- Emilia A Lubecka
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland.
| | - Emilia Sikorska
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland
| | - Dariusz Sobolewski
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland
| | - Adam Prahl
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland
| | - Jiřina Slaninová
- Institute of Organic Chemistry and Biochemistry, Academy of Sciences of the Czech Republic, 166 10, Prague, Czech Republic
| | - Jerzy Ciarkowski
- Faculty of Chemistry, University of Gdańsk, Wita Stwosza 63, 80-308, Gdańsk, Poland
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9
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Kulkarni AK, Ojha RP. Conformations of a model cyclic hexapeptide, CYIQNC: (1)H-NMR and molecular dynamics studies. J Biomol Struct Dyn 2014; 33:1850-65. [PMID: 25375824 DOI: 10.1080/07391102.2014.975283] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Solution conformation of the cyclic hexapeptide sequence, [cyclo-S-Cys-Tyr-Ile-Gln-Asn-Cys-S] (CYIQNC) - a disulfide-linked fragment of a neurohypophyseal peptide hormone oxytocin (OT) - has been investigated by high-field one-dimensional (1D) and two-dimensional (2D) NMR spectroscopic methods and compared with the results obtained from computer simulation studies. (1)H-NMR results based on temperature dependence of amide proton chemical shifts and nuclear Overhauser effect indicate that peptide in solution populates different conformations, characterized by two fused β-turns. The segment Ile(3)-Gln(4)-Asn(5)-Cys(6) yields a preferred type-III β-turn at residues 4, 5 (HB, 3HN → 6CO), while the segment Cys(6), Cys(1)-Tyr(2)-Ile(3) exhibits inherently weaker, flexible β-turn either of type I/II'/III/half-turn at residues 1, 2 (HB, 6HN → 3CO). The computer simulation studies using a mixed protocol of distance geometry-simulated annealing followed by constrained minimization, restrained molecular dynamics, and energy minimization showed the possibility of existence of additional conformations with the hydrogen bonds, (a) 5HN → 3CO and (b) 2HN → 6CO. These results, therefore, indicate that the additional conformations obtained from both NMR and simulation studies can also be possible to the peptide. These additional conformations might have very small population in the solution and did not show their signatures in these conditions. These findings will be helpful in designing more analogs with modifications in the cyclic moiety of OT.
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Affiliation(s)
- Ashok Kumar Kulkarni
- a Department of Physiology , MediCiti Institute of Medical Sciences , Ghanpur, Medchal Mandal, R. R. Dist., Hyderabad 501401 , India
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10
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Haensele E, Banting L, Whitley DC, Clark T. Conformation and dynamics of 8-Arg-vasopressin in solution. J Mol Model 2014; 20:2485. [DOI: 10.1007/s00894-014-2485-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2014] [Accepted: 10/06/2014] [Indexed: 01/12/2023]
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11
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Yedvabny E, Nerenberg PS, So C, Head-Gordon T. Disordered structural ensembles of vasopressin and oxytocin and their mutants. J Phys Chem B 2014; 119:896-905. [PMID: 25231121 DOI: 10.1021/jp505902m] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Vasopressin and oxytocin are intrinsically disordered cyclic nonapeptides belonging to a family of neurohypophysial hormones. Although unique in their functions, these peptides differ only by two residues and both feature a tocin ring formed by the disulfide bridge between first and sixth cysteine residues. This sequence and structural similarity are experimentally linked to oxytocin agonism at vasopressin receptors and vasopressin antagonism at oxytocin receptors. Yet single- or double-residue mutations in both peptides have been shown to have drastic impacts on their activities at either receptor, and possibly the ability to bind to their neurophysin carrier protein. In this study we perform molecular dynamics simulations of the unbound native and mutant sequences of the oxytocin and vasopressin hormones to characterize their structural ensembles. We classify the subpopulations of these structural ensembles on the basis of the distributions of radius of gyration and secondary structure and hydrogen-bonding features of the canonical tocin ring and disordered tail region. We then relate the structural changes observed in the unbound form of the different hormone sequences to experimental information about peptide receptor binding, and more indirectly, carrier protein binding affinity, receptor activity, and protease degradation. This study supports the hypothesis that the structural characteristics of the unbound form of an IDP can be used to predict structural or functional preferences of its functional bound form.
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Affiliation(s)
- Eugene Yedvabny
- Department of Chemistry, ‡Department of Bioengineering, and §Department of Chemical and Biomolecular Engineering, University of California , Berkeley, California 94720-3220, United States
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12
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Lubecka EA, Sikorska E, Marcinkowska A, Ciarkowski J. Conformational studies of neurohypophyseal hormones analogues with glycoconjugates by NMR spectroscopy. J Pept Sci 2014; 20:406-14. [DOI: 10.1002/psc.2628] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Revised: 02/18/2014] [Accepted: 02/21/2014] [Indexed: 11/05/2022]
Affiliation(s)
- Emilia A. Lubecka
- Faculty of Chemistry; University of Gdańsk; Wita Stwosza 63 80-952 Gdańsk Poland
| | - Emilia Sikorska
- Faculty of Chemistry; University of Gdańsk; Wita Stwosza 63 80-952 Gdańsk Poland
| | - Alina Marcinkowska
- Faculty of Chemistry; University of Gdańsk; Wita Stwosza 63 80-952 Gdańsk Poland
| | - Jerzy Ciarkowski
- Faculty of Chemistry; University of Gdańsk; Wita Stwosza 63 80-952 Gdańsk Poland
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13
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Avanti C, Oktaviani NA, Hinrichs WLJ, Frijlink HW, Mulder FAA. Aspartate buffer and divalent metal ions affect oxytocin in aqueous solution and protect it from degradation. Int J Pharm 2013; 444:139-45. [PMID: 23376504 DOI: 10.1016/j.ijpharm.2013.01.051] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Revised: 01/22/2013] [Accepted: 01/24/2013] [Indexed: 11/25/2022]
Abstract
Oxytocin is a peptide drug used to induce labor and prevent bleeding after childbirth. Due to its instability, transport and storage of oxytocin formulations under tropical conditions is problematic. In a previous study, we have found that the stability of oxytocin in aspartate buffered formulation is improved by the addition of divalent metal ions (unpublished results). The stabilizing effect of Zn(2+) was by far superior compared to that of Mg(2+). In addition, it was found that stabilization correlated well with the ability of the divalent metal ions to interact with oxytocin in aspartate buffer. Furthermore, LC-MS (MS) measurements indicated that the combination of aspartate buffer and Zn(2+) in particular suppressed intermolecular degradation reactions near the Cys(1,6) disulfide bridge. These results lead to the hypothesis that in aspartate buffer, Zn(2+) changes the conformation of oxytocin in such a way that the Cys(1,6) disulfide bridge is shielded from its environment thereby suppressing intermolecular reactions involving this region of the molecule. To verify this hypothesis, we investigate here the conformation of oxytocin in aspartate buffer in the presence of Mg(2+) or Zn(2+), using 2D NOESY, TOCSY, (1)H-(13)C HSQC and (1)H-(15)N HSQC NMR spectroscopy. Almost all (1)H, (13)C and (15)N resonances of oxytocin could be assigned using HSQC spectroscopy, without the need for (13)C or (15)N enrichment. (1)H-(13)C and (1)H-(15)N HSQC spectra showed that aspartate buffer alone induces minor changes in oxytocin in D2O, with the largest chemical shift changes observed for Cys(1). Zn(2+) causes more extensive changes in oxytocin in aqueous solution than Mg(2+). Our findings suggest that the carboxylate group of aspartate neutralizes the positive charge of the N-terminus of Cys(1), allowing the interactions with Zn(2+) to become more favorable. These interactions may explain the protection of the disulfide bridge against intermolecular reactions that lead to dimerization.
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Affiliation(s)
- Christina Avanti
- Department of Pharmaceutical Technology and Biopharmacy, University of Groningen, Antonius Deusinglaan 1, 9713 AV, Groningen, The Netherlands.
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14
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Sikorska E, Iłowska E, Wyrzykowski D, Kwiatkowska A. Membrane structure and interactions of peptide hormones with model lipid bilayers. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:2982-93. [DOI: 10.1016/j.bbamem.2012.07.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2012] [Revised: 07/10/2012] [Accepted: 07/16/2012] [Indexed: 11/26/2022]
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15
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Sikorska E, Kwiatkowska A. Micelle-bound conformations of neurohypophyseal hormone analogues modified with a Cα-disubstituted residue: NMR and molecular modelling studies. J Biomol Struct Dyn 2012; 31:748-64. [PMID: 22908889 DOI: 10.1080/07391102.2012.709459] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Abstract
In this study, by applying a combined approach of NMR measurements and molecular modelling, the conformations and the interactions with membrane-like environment of five arginine vasopressin (AVP) or oxytocin (OT) analogues modified with Cα-disubstituted cis-1-amino-4-phenylcyclohexane-1-carboxylic acid in position 2 have been determined. In addition, the AVP analogues were prepared in N-acylated forms with various bulky acyl groups. All of the peptides studied interacted with the mixed dodecylphosphocholine:sodium dodecyl sulphate micelle, providing a model of biological membrane. A different polarities of the AVP- and OT-like peptides resulted in their different position relative to the micelle surface. Thus, the arrangement of the former was nearly perpendicular, whereas the latter was rather parallel to the micelle's surface. Moreover, the results of our studies have shown that the binding sites for antagonists may be overlapped with that for agonists, as well as it may be quite different. Nevertheless, the aromatic-aromatic contacts represent the most important interactions for antagonists, whereas the hydrophilic interactions seem to be crucial for agonists.
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Affiliation(s)
- Emilia Sikorska
- Faculty of Chemistry, University of Gdańsk, Sobieskiego 18, 80-952, Gdańsk, Poland.
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Pazderková M, Bednárová L, Dlouhá H, Flegel M, Lebl M, Hlaváček J, Setnička V, Urbanová M, Hynie S, Klenerová V, Baumruk V, Maloň P. Electronic and vibrational optical activity of several peptides related to neurohypophyseal hormones: Disulfide group conformation. Biopolymers 2012; 97:923-32. [DOI: 10.1002/bip.22105] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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