1
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Kuwana Y, Ashizawa Y, Ajima M, Nomura T, Kakeno M, Hirai S, Miura T. Micelle-associated endomorphin-1 has ability to bind copper in the oxidation state either Cu(II) or Cu(I). Arch Biochem Biophys 2022; 727:109305. [DOI: 10.1016/j.abb.2022.109305] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2022] [Revised: 05/16/2022] [Accepted: 05/27/2022] [Indexed: 11/24/2022]
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2
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Schwartz AC, Jay DW, Parnham S, Giuliano MW. Sequential and Environmental Dependence of Conformation in a Small Opioid Peptide. J Org Chem 2019; 84:13299-13312. [PMID: 31538782 DOI: 10.1021/acs.joc.9b01141] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report the structural characterization of the μ-selective endogenous opioid endomorphin-1 (EM-1) via an array of nuclear magnetic resonance experiments in both aqueous conditions and, for the first time, in isotropic lipid bicelles, which mimic its endogenous environment. Consistent with computationally derived hypotheses, EM-1 is found to significantly populate a compact, turn-like structure in aqueous solution. This structure is only present as a minor species when the peptide is subjected to a lipid environment, in which the presented NMR data suggests that the major conformer of EM-1 lacks internal hydrogen bonds. The interaction of EM-1 with lipid bilayers is characterized by both tryptophan fluorescence and two-dimensional diffusion ordered NMR spectroscopy; these experiments suggest that the interaction with the surface of phospholipid bilayers, operating as a change in bulk solvation, is responsible for the observed conformational rearrangement in EM-1.
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Affiliation(s)
- Alexandra C Schwartz
- Department of Chemistry and Biochemistry , College of Charleston , Charleston , South Carolina 29424 , United States
| | - Dashiell W Jay
- Department of Chemistry and Biochemistry , College of Charleston , Charleston , South Carolina 29424 , United States
| | - Stuart Parnham
- Department of Biochemistry and Molecular Biology , Medical University of South Carolina , Charleston , South Carolina 29425 , United States
| | - Michael W Giuliano
- Department of Chemistry and Biochemistry , College of Charleston , Charleston , South Carolina 29424 , United States
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3
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Wtorek K, Artali R, Piekielna-Ciesielska J, Koszuk J, Kluczyk A, Gentilucci L, Janecka A. Endomorphin-2 analogs containing modified tyrosines: Biological and theoretical investigation of the influence on conformation and pharmacological profile. Eur J Med Chem 2019; 179:527-536. [PMID: 31276897 DOI: 10.1016/j.ejmech.2019.06.077] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 06/26/2019] [Accepted: 06/27/2019] [Indexed: 11/16/2022]
Abstract
New analogs of the endogenous opioid agonist endomorphin-2 (EM-2, H-Tyr-Pro-Phe-Phe-NH2) have been obtained by introducing modified tyrosines at the position 1 of the sequence. For all analogs, the cis/trans conformation ratio about the tyramine-Pro amide bond, lipophilicity, receptor affinities, and functional activities, have been determined. Among the novel derivatives, [Dmt(3'-Cl)]1EM-2 (4) stood out for its subnanomolar μ-opioid receptor affinity and potent agonist activity, superior to that of the parent peptide EM-2. Hybrid quantum mechanics/molecular mechanics docking computations supported the cis tyramine-Pro bioactive conformation, and allowed us to analyze the contribution of the substituents of the "message" tyramine to binding, highlighting the role of halogen-bonding in the higher receptor affinity of peptide 4.
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Affiliation(s)
- Karol Wtorek
- Department of Biomolecular Chemistry, Medical University of Lodz, Mazowiecka 6/8, 92-215, Lodz, Poland
| | - Roberto Artali
- Scientia Advice, di Roberto Artali, 20832, Desio, Monza and Brianza, Italy
| | | | - Jacek Koszuk
- Institute of Organic Chemistry, Lodz University of Technology, Lodz, Poland
| | - Alicja Kluczyk
- Faculty of Chemistry, University of Wroclaw, Wroclaw, Poland
| | - Luca Gentilucci
- Department of Chemistry, University of Bologna, Via Selmi 2, 40126, Bologna, Italy.
| | - Anna Janecka
- Department of Biomolecular Chemistry, Medical University of Lodz, Mazowiecka 6/8, 92-215, Lodz, Poland.
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4
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Manna S, Panse CH, Sontakke VA, Sangamesh S, Srivatsan SG. Probing Human Telomeric DNA and RNA Topology and Ligand Binding in a Cellular Model by Using Responsive Fluorescent Nucleoside Probes. Chembiochem 2017; 18:1604-1615. [PMID: 28569423 PMCID: PMC5724660 DOI: 10.1002/cbic.201700283] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2017] [Indexed: 01/03/2023]
Abstract
The development of biophysical systems that enable an understanding of the structure and ligand-binding properties of G-quadruplex (GQ)-forming nucleic acid sequences in cells or models that mimic the cellular environment would be highly beneficial in advancing GQ-directed therapeutic strategies. Herein, the establishment of a biophysical platform to investigate the structure and recognition properties of human telomeric (H-Telo) DNA and RNA repeats in a cell-like confined environment by using conformation-sensitive fluorescent nucleoside probes and a widely used cellular model, bis(2-ethylhexyl) sodium sulfosuccinate reverse micelles (RMs), is described. The 2'-deoxy and ribonucleoside probes, composed of a 5-benzofuran uracil base analogue, faithfully report the aqueous micellar core through changes in their fluorescence properties. The nucleoside probes incorporated into different loops of H-Telo DNA and RNA oligonucleotide repeats are minimally perturbing and photophysically signal the formation of respective GQ structures in both aqueous buffer and RMs. Furthermore, these sensors enable a direct comparison of the binding affinity of a ligand to H-Telo DNA and RNA GQ structures in the bulk and confined environment of RMs. These results demonstrate that this combination of a GQ nucleoside probe and easy-to-handle RMs could provide new opportunities to study and devise screening-compatible assays in a cell-like environment to discover GQ binders of clinical potential.
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Affiliation(s)
- Sudeshna Manna
- Department of ChemistryIndian Institute of Science Education and Research (IISER)Dr. Homi Bhabha RoadPune411008India
| | - Cornelia H. Panse
- Department of ChemistryIndian Institute of Science Education and Research (IISER)Dr. Homi Bhabha RoadPune411008India
| | - Vyankat A. Sontakke
- Department of ChemistryIndian Institute of Science Education and Research (IISER)Dr. Homi Bhabha RoadPune411008India
| | - Sarangamath Sangamesh
- Department of ChemistryIndian Institute of Science Education and Research (IISER)Dr. Homi Bhabha RoadPune411008India
| | - Seergazhi G. Srivatsan
- Department of ChemistryIndian Institute of Science Education and Research (IISER)Dr. Homi Bhabha RoadPune411008India
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5
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Liu Y, Chen Y, Yao Y, Luo K, Zhang S, Gu Z. Confined Pool-Buried Water-Soluble Nanoparticles from Reverse Micelles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2017; 33:5275-5282. [PMID: 28505441 DOI: 10.1021/acs.langmuir.7b00890] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
With the special nature of confined water pools, reverse micelles (RMs) have shown potential for a wide range of applications. However, the inherent water insolubility of RMs hinders their further application prospect especially for applications related to biology. We present herein the first successful transformation of water-insoluble RMs into water-soluble nanoparticles without changing the confined aqueous interiors by hydrolysis/aminolysis of arm-cleavable interfacial cross-linked reverse micelles formed from diester surfactant 1. The unique properties exhibited by the aqueous interiors of the resulting pool-buried water-soluble nanoparticles (PWNPs) were demonstrated both by the template synthesis of gold nanoparticles in the absence of external reductants and by the fluorescence enhancement of encapsulated thioflavin T (ThT). Importantly, the unique potential for PWNPs in biological applications was exemplified by the use of ThT@PWNPs and "cell targeted" ThT@PWNPs as effective optical imaging agents of living cells. This work conceptually overcomes the application bottleneck of RMs and opens an entry to a new class of functional materials.
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Affiliation(s)
- Yong Liu
- National Engineering Research Center for Biomaterials and ‡College of Chemistry, Sichuan University , 29 Wangjiang Road, Chengdu 610064, China
| | - Ying Chen
- National Engineering Research Center for Biomaterials and ‡College of Chemistry, Sichuan University , 29 Wangjiang Road, Chengdu 610064, China
| | - Yongchao Yao
- National Engineering Research Center for Biomaterials and ‡College of Chemistry, Sichuan University , 29 Wangjiang Road, Chengdu 610064, China
| | - Kui Luo
- National Engineering Research Center for Biomaterials and ‡College of Chemistry, Sichuan University , 29 Wangjiang Road, Chengdu 610064, China
| | - Shiyong Zhang
- National Engineering Research Center for Biomaterials and ‡College of Chemistry, Sichuan University , 29 Wangjiang Road, Chengdu 610064, China
| | - Zhongwei Gu
- National Engineering Research Center for Biomaterials and ‡College of Chemistry, Sichuan University , 29 Wangjiang Road, Chengdu 610064, China
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6
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Pastore A, Temussi P. When "IUPs" were "BAPs": How to study the nonconformation of intrinsically unfolded polyaminoacid chains. Biopolymers 2016; 100:592-600. [PMID: 23896858 DOI: 10.1002/bip.22363] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Accepted: 07/12/2013] [Indexed: 01/21/2023]
Abstract
Ideas often recur. It has been pointed out recently that proteins are not always the well-structured entities we have become accustomed to from crystallographic studies, but may be intrinsically unstructured or contain unstructured regions. This feature, far from making these proteins less interesting, is an essential requirement for their function. Fascinating though it may be, the concept of so-called intrinsically unfolded (or unordered) proteins (IUPs), also often referred to as intrinsically disordered proteins (IDPs), is not new: it directly links back to the 1970s when the attention of many structural biologists was focused on biologically active peptides, which like IUPs lack a specific defined conformation. The recurrent nature of this concept may now be of topical interest since it suggests the transfer, upon suitable adaptation, of old tools to develop new ideas. Here, we review some of the approaches that were developed for the study of peptides and discuss how they could inspire powerful new methodologies for the study of IUPs.
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Affiliation(s)
- Annalisa Pastore
- National Institute for Medical Research, The Ridgeway, London, NW7 1AA, United Kingdom
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7
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Li Y, Cazares M, Wu J, Houghten RA, Toll L, Dooley C. Potent μ-Opioid Receptor Agonists from Cyclic Peptides Tyr-c[D-Lys-Xxx-Tyr-Gly]: Synthesis, Biological, and Structural Evaluation. J Med Chem 2016; 59:1239-45. [PMID: 26789491 DOI: 10.1021/acs.jmedchem.5b01899] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
To optimize the structure of a μ-opioid receptor ligand, analogs H-Tyr-c[D-Lys-Xxx-Tyr-Gly] were synthesized and their biological activity was tested. The analog containing a Phe(3) was identified as not only exhibiting binding affinity 14-fold higher than the original hit but also producing agonist activity 3-fold more potent than morphine. NMR study suggested that a trans conformation at D-Lys(2)-Xxx(3) is crucial for these cyclic peptides to maintain high affinity, selectivity, and functional activity toward the μ-opioid receptor.
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Affiliation(s)
- Yangmei Li
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Margret Cazares
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Jinhua Wu
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Richard A Houghten
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Laurence Toll
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
| | - Colette Dooley
- Torrey Pines Institute for Molecular Studies , 11350 SW Village Parkway, Port St. Lucie, Florida 34987, United States
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8
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Mollica A, Costante R, Stefanucci A, Pinnen F, Luisi G, Pieretti S, Borsodi A, Bojnik E, Benyhe S. Hybrid peptides endomorphin-2/DAMGO: Design, synthesis and biological evaluation. Eur J Med Chem 2013; 68:167-77. [DOI: 10.1016/j.ejmech.2013.07.044] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2013] [Revised: 07/03/2013] [Accepted: 07/05/2013] [Indexed: 02/07/2023]
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9
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Wang CL, Ren YK, Xiang Q, Wang Y, Gu N, Lu C, Wang R. Characterization of opioid activities of endomorphin analogs with C-terminal amide to hydrazide conversion. Neuropeptides 2013; 47:297-304. [PMID: 24084335 DOI: 10.1016/j.npep.2013.09.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/04/2013] [Revised: 08/31/2013] [Accepted: 09/09/2013] [Indexed: 11/29/2022]
Abstract
Previously, we have synthesized an endomorphin-2 (EM-2) analog with C-terminal amide to hydrazide conversion, exhibiting slightly lower μ-affinity than EM-2. In the present study, the influence of C-terminal amide group to hydrazide conversion on the in vitro and in vivo opioid activities of EMs was evaluated. Our results demonstrated that C-terminal amide to hydrazide conversion of EMs did not markedly change their μ-opioid receptor binding affinities. Nevertheless, EM-2-NHNH2 decreased guinea pig ileum (GPI) and mouse vas deferens (MVD) potencies by about 10- and 5-fold compared to the parent compound, respectively. It is noteworthy that EM-1-NHNH2 exhibited the highest antinociception after intracerebroventricular (i.c.v.) injection, about 1.5-fold more potent than EM-1, but with moderate colonic contractile and expulsive effects, comparable with EM-1. Additionally, though EM-2-NHNH2 showed a slightly lower antinociceptive effect than EM-2, at higher doses (i.c.v., 1.5 and 5 nmol/mouse) the inhibitory effects of colonic propulsion were significantly attenuated, which would be helpful in the development of suitable μ-opioid therapeutics, but without some undesirable side effects. Therefore, the present results gave the evidence that C-terminal amide to hydrazide conversion of EMs may play an important role in the regulation of opioid activities.
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Affiliation(s)
- Chang-Lin Wang
- School of Life Science and Technology, State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, 92 West Dazhi Street, Harbin 150001, China.
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10
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Chaudhuri A, Basu P, Haldar S, Kombrabail M, Krishnamoorthy G, Rajarathnam K, Chattopadhyay A. Organization and dynamics of the N-terminal domain of chemokine receptor CXCR1 in reverse micelles: effect of graded hydration. J Phys Chem B 2013; 117:1225-33. [PMID: 23311880 DOI: 10.1021/jp3095352] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Water plays a fundamental role in the folding, structure, dynamics, and function of proteins and peptides. The extracellular N-terminal domain of chemokine receptors is crucial in mediating binding affinity, receptor selectivity, and regulating function. The flexible N-terminal domain becomes ordered in membranes and membrane-mimetic assemblies, thereby indicating that the membrane could play an important role in regulating CXC chemokine receptor 1 (CXCR1) function. In view of the role of hydration in lipid-protein interactions in membranes, we explored the organization and dynamics of a 34-mer peptide of the CXCR1 N-terminal domain in reverse micelles by utilizing a combination of fluorescence-based approaches and circular dichroism spectroscopy. Our results show that the secondary structure adopted by the CXCR1 N-domain is critically dependent on hydration. The tryptophan residues of the CXCR1 N-domain experience motional restriction and exhibit red edge excitation shift (REES) upon incorporation in reverse micelles. REES and fluorescence lifetime exhibit reduction with increasing reverse micellar hydration. Time-resolved fluorescence anisotropy measurements reveal the effect of hydration on peptide rotational dynamics. Taken together, these results constitute the first report demonstrating modulation in the organization and dynamics of the N-terminal domain of a chemokine receptor in a membrane-like environment of varying hydration. We envisage that these results are relevant in the context of hydration in the function of G protein-coupled receptors.
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Affiliation(s)
- Arunima Chaudhuri
- Centre for Cellular and Molecular Biology, Council of Scientific and Industrial Research, Uppal Road, Hyderabad 500 007, India
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11
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Correa NM, Silber JJ, Riter RE, Levinger NE. Nonaqueous Polar Solvents in Reverse Micelle Systems. Chem Rev 2012; 112:4569-602. [DOI: 10.1021/cr200254q] [Citation(s) in RCA: 204] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- N. Mariano Correa
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia
Postal #3, C.P. X5804BYA Río Cuarto, Argentina
| | - Juana J. Silber
- Departamento de Química, Universidad Nacional de Río Cuarto, Agencia
Postal #3, C.P. X5804BYA Río Cuarto, Argentina
| | - Ruth E. Riter
- Department of Chemistry, Agnes Scott College, Decatur, Georgia 30030-3770, United
States
| | - Nancy E. Levinger
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80523-1872,
United States
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12
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Vincent M, Gallay J. Water gradient in the membrane-water interface: a time-resolved study of the series of n-(9-anthroyloxy) stearic acids incorporated in AOT/water/iso-octane reverse micelles. J Phys Chem B 2012; 116:1687-99. [PMID: 22233168 DOI: 10.1021/jp209419y] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The water radial distribution in AOT/iso-octane/water reverse micelles (RM), used to mimic the membrane-water interface, was examined by excited-state lifetime and transient spectral measurements of the series of n-(9-anthroyloxy) stearic acids (n-AS), with n = 2, 3, 6, 7, 9, 10, and 12. A water gradient in the RM extended from the polar head group region up to the middle of the surfactant carbon chains. A fast intramolecular excited-state relaxation, involving the rotation of the carboxylic group of the ester bond with respect to the anthracene ring, gave rise to a nanosecond time-dependent fluorescence Stokes shifts (TDFSS). In water-filled RMs, we only observed a water-induced TDFSS occurring over subnano- and nanosecond time scales with decreasing amplitudes and rates as a function of depth, according to the decreasing water gradient and the slowing down of the anthroyloxy moiety rotational motion. This water-induced TDFSS is most likely the result of both H-bond formation and general dipolar relaxation, as indirectly showed by measurements with DMF (a nonprotic polar solvent) instead of water in RMs.
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Affiliation(s)
- Michel Vincent
- Institut de Biochimie et de Biophysique Moléculaire et Cellulaire, Université Paris-Sud, UMR 8619-CNRS, F-91405 Orsay, France.
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13
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Leitgeb B. Conformational similarities and dissimilarities between the stereoisomeric forms of endomorphin-2. Chem Biol Drug Des 2011; 79:313-25. [PMID: 22117819 DOI: 10.1111/j.1747-0285.2011.01275.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this study, taking into account both the l-d and cis-trans isomerisms, a comprehensive structural characterization and a comparative conformational analysis were performed on the 32 stereoisomeric forms of opioid tetrapeptide, endomorphin-2. For all stereoisomers, the Φ-Ψ and χ conformational spaces were explored, in the course of which the conformational distributions, as well as the rotamer states of aromatic side chains were characterized in detail. Furthermore, the typical β- and γ-turn structures, as well as the characteristic intramolecular interactions (i.e., H-bonds, aromatic-aromatic and proline-aromatic interplays) were determined. The afore-mentioned structural and conformational features identified for each stereoisomeric form were compared with one another, considering all 32 stereoisomers. The results obtained from this comparative study indicated that both similarities and dissimilarities could be observed between the stereoisomeric forms, with regard to their structural and conformational properties. This theoretical work supplied several valuable observations concerning the effects of both l-d and cis-trans isomerisms on the three-dimensional structure of parent peptide and its stereoisomers. Nevertheless, in the course of this structural investigation, it was clarified how the structural and conformational features of stereoisomeric forms differed from one another.
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Affiliation(s)
- Balázs Leitgeb
- Institute of Biophysics, Biological Research Center of the Hungarian Academy of Sciences, Szeged, Hungary.
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14
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Four-component pharmacophore model for endomorphins toward μ opioid receptor subtypes. J Mol Model 2011; 18:825-34. [DOI: 10.1007/s00894-011-1108-2] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2011] [Accepted: 04/25/2011] [Indexed: 10/18/2022]
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15
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16
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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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17
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Zdobinsky T, Scherkenbeck J, Zerbe O, Antonicek H, Chen H. Structures of Micelle-Bound Selected Insect Neuropeptides and Analogues: Implications for Receptor Selection. Chembiochem 2009; 10:2644-53. [DOI: 10.1002/cbic.200900450] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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18
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Wang Y, Wu Y, Chen J, Huang LS, Tsai F, Hwang C. Structure–activity relationships of modified C-terminal endomorphin-2 analogues by molecular dynamics simulations. J Mol Graph Model 2008; 27:489-96. [DOI: 10.1016/j.jmgm.2008.08.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2008] [Revised: 08/28/2008] [Accepted: 08/29/2008] [Indexed: 02/07/2023]
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19
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Keresztes A, Szűcs M, Borics A, Kövér KE, Forró E, Fülöp F, Tömböly C, Péter A, Páhi A, Fábián G, Murányi M, Tóth G. New Endomorphin Analogues Containing Alicyclic β-Amino Acids: Influence on Bioactive Conformation and Pharmacological Profile. J Med Chem 2008; 51:4270-9. [DOI: 10.1021/jm800223t] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Attila Keresztes
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary, Department of Chemistry, University of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary, Department of Inorganic and Analytical Chemistry, Dóm tér 7, University of Szeged, H-6720 Szeged, Hungary
| | - Mária Szűcs
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary, Department of Chemistry, University of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary, Department of Inorganic and Analytical Chemistry, Dóm tér 7, University of Szeged, H-6720 Szeged, Hungary
| | - Attila Borics
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary, Department of Chemistry, University of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary, Department of Inorganic and Analytical Chemistry, Dóm tér 7, University of Szeged, H-6720 Szeged, Hungary
| | - Katalin E. Kövér
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary, Department of Chemistry, University of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary, Department of Inorganic and Analytical Chemistry, Dóm tér 7, University of Szeged, H-6720 Szeged, Hungary
| | - Enikő Forró
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary, Department of Chemistry, University of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary, Department of Inorganic and Analytical Chemistry, Dóm tér 7, University of Szeged, H-6720 Szeged, Hungary
| | - Ferenc Fülöp
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary, Department of Chemistry, University of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary, Department of Inorganic and Analytical Chemistry, Dóm tér 7, University of Szeged, H-6720 Szeged, Hungary
| | - Csaba Tömböly
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary, Department of Chemistry, University of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary, Department of Inorganic and Analytical Chemistry, Dóm tér 7, University of Szeged, H-6720 Szeged, Hungary
| | - Antal Péter
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary, Department of Chemistry, University of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary, Department of Inorganic and Analytical Chemistry, Dóm tér 7, University of Szeged, H-6720 Szeged, Hungary
| | - Annamária Páhi
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary, Department of Chemistry, University of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary, Department of Inorganic and Analytical Chemistry, Dóm tér 7, University of Szeged, H-6720 Szeged, Hungary
| | - Gabriella Fábián
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary, Department of Chemistry, University of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary, Department of Inorganic and Analytical Chemistry, Dóm tér 7, University of Szeged, H-6720 Szeged, Hungary
| | - Mariann Murányi
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary, Department of Chemistry, University of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary, Department of Inorganic and Analytical Chemistry, Dóm tér 7, University of Szeged, H-6720 Szeged, Hungary
| | - Géza Tóth
- Institute of Biochemistry, Biological Research Center, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary, Institute of Pharmaceutical Chemistry, University of Szeged, Eötvös utca 6, H-6720 Szeged, Hungary, Department of Chemistry, University of Debrecen, P.O. Box 21, H-4010 Debrecen, Hungary, Department of Inorganic and Analytical Chemistry, Dóm tér 7, University of Szeged, H-6720 Szeged, Hungary
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20
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Leitgeb B. Structural Investigation of Endomorphins by Experimental and Theoretical Methods: Hunting for the Bioactive Conformation. Chem Biodivers 2007; 4:2703-24. [DOI: 10.1002/cbdv.200790221] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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21
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Li T, Shiotani K, Miyazaki A, Tsuda Y, Ambo A, Sasaki Y, Jinsmaa Y, Marczak E, Bryant SD, Lazarus LH, Okada Y. Bifunctional [2',6'-dimethyl-L-tyrosine1]endomorphin-2 analogues substituted at position 3 with alkylated phenylalanine derivatives yield potent mixed mu-agonist/delta-antagonist and dual mu-agonist/delta-agonist opioid ligands. J Med Chem 2007; 50:2753-66. [PMID: 17497839 PMCID: PMC2669435 DOI: 10.1021/jm061238m] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Endomorphin-2 (H-Tyr-Pro-Phe-Phe-NH2) and [Dmt1]EM-2 (Dmt = 2',6'-dimethyl-l-tyrosine) analogues, containing alkylated Phe3 derivatives, 2'-monomethyl (2, 2'), 3',5'- and 2',6'-dimethyl (3, 3', and 4', respectively), 2',4',6'-trimethyl (6, 6'), 2'-ethyl-6'-methyl (7, 7'), and 2'-isopropyl-6'-methyl (8, 8') groups or Dmt (5, 5'), had the following characteristics: (i) [Xaa3]EM-2 analogues exhibited improved mu- and delta-opioid receptor affinities. The latter, however, were inconsequential (Kidelta = 491-3451 nM). (ii) [Dmt1,Xaa3]EM-2 analogues enhanced mu- and delta-opioid receptor affinities (Kimu = 0.069-0.32 nM; Kidelta = 1.83-99.8 nM) without kappa-opioid receptor interaction. (iii) There were elevated mu-bioactivity (IC50 = 0.12-14.4 nM) and abolished delta-agonism (IC50 > 10 muM in 2', 3', 4', 5', 6'), although 4' and 6' demonstrated a potent mixed mu-agonism/delta-antagonism (for 4', IC50mu = 0.12 and pA2 = 8.15; for 6', IC50mu = 0.21 nM and pA2 = 9.05) and 7' was a dual mu-agonist/delta-agonist (IC50mu = 0.17 nM; IC50delta = 0.51 nM).
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MESH Headings
- Animals
- Binding, Competitive
- Brain/metabolism
- Guinea Pigs
- In Vitro Techniques
- Ligands
- Male
- Mice
- Muscle Contraction/drug effects
- Muscle, Smooth/drug effects
- Muscle, Smooth/innervation
- Muscle, Smooth/physiology
- Myenteric Plexus/physiology
- Neuromuscular Junction/drug effects
- Neuromuscular Junction/physiology
- Oligopeptides/chemical synthesis
- Oligopeptides/pharmacology
- Radioligand Assay
- Rats
- Rats, Sprague-Dawley
- Receptors, Opioid, delta/agonists
- Receptors, Opioid, delta/antagonists & inhibitors
- Receptors, Opioid, mu/agonists
- Structure-Activity Relationship
- Synaptosomes/metabolism
- Tyrosine/analogs & derivatives
- Tyrosine/chemical synthesis
- Tyrosine/pharmacology
- Vas Deferens/drug effects
- Vas Deferens/physiology
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Affiliation(s)
- Tingyou Li
- The Graduate School of Food and Medicinal Sciences, Kobe Gakuin University, Nishi-ku, Kobe 651-2180, Japan
| | - Kimitaka Shiotani
- The Graduate School of Food and Medicinal Sciences, Kobe Gakuin University, Nishi-ku, Kobe 651-2180, Japan
| | - Anna Miyazaki
- Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Nishi-ku, Kobe 651-2180, Japan
| | - Yuko Tsuda
- The Graduate School of Food and Medicinal Sciences, Kobe Gakuin University, Nishi-ku, Kobe 651-2180, Japan
- Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Nishi-ku, Kobe 651-2180, Japan
| | - Akihiro Ambo
- Department of Biochemistry, Tohoku Pharmaceutical University, Aoba-ku, Sendai 981-8558, Japan
| | - Yusuke Sasaki
- Department of Biochemistry, Tohoku Pharmaceutical University, Aoba-ku, Sendai 981-8558, Japan
| | - Yunden Jinsmaa
- Medicinal Chemistry Group, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, U.S.A
| | - Ewa Marczak
- Medicinal Chemistry Group, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, U.S.A
| | - Sharon D. Bryant
- Medicinal Chemistry Group, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, U.S.A
| | - Lawrence H. Lazarus
- Medicinal Chemistry Group, Laboratory of Pharmacology and Chemistry, National Institute of Environmental Health Sciences, Research Triangle Park, NC 27709, U.S.A
- Corresponding authors: Y. Okada: Tel: +81-78-974-1551, fax: +81-78-974-5689., E-mail: . L. H. Lazarus: Tel: +1-919-541-3238, fax: + 1-919-541-5737. E-mail:
| | - Yoshio Okada
- The Graduate School of Food and Medicinal Sciences, Kobe Gakuin University, Nishi-ku, Kobe 651-2180, Japan
- Faculty of Pharmaceutical Sciences, Kobe Gakuin University, Nishi-ku, Kobe 651-2180, Japan
- Corresponding authors: Y. Okada: Tel: +81-78-974-1551, fax: +81-78-974-5689., E-mail: . L. H. Lazarus: Tel: +1-919-541-3238, fax: + 1-919-541-5737. E-mail:
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22
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Shao X, Gao Y, Zhu C, Liu X, Yao J, Cui Y, Wang R. Conformational analysis of endomorphin-2 analogs with phenylalanine mimics by NMR and molecular modeling. Bioorg Med Chem 2007; 15:3539-47. [PMID: 17368034 DOI: 10.1016/j.bmc.2007.02.050] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2006] [Revised: 02/22/2007] [Accepted: 02/23/2007] [Indexed: 11/20/2022]
Abstract
We investigated a series of conformations of endomorphin-2 (EM-2) analogs substituted by phenylglycine (Phg) and homophenylalanine (Hfe) in the position 3 or 4 by two-dimensional (1)H NMR spectroscopy and molecular modeling. Evaluating the aromatic interactions and the dihedral angles in these phenylalanine mimics, we have observed that the conformations in trans isomer have varied from extended to folded as bioactivity decreases. It is suggested that the flexibility of aromatic side chain affects the backbone of EM-2 to adopt folded structures, which may block the ligands in binding to micro-opioid receptor.
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Affiliation(s)
- Xuan Shao
- State Key Laboratory of Applied Organic Chemistry, Institute of Biochemistry and Molecular Biology, School of Life Science, Lanzhou University, Lanzhou 730000, People's Republic of China
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23
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Yu Y, Shao X, Wang CL, Liu HM, Cui Y, Fan YZ, Liu J, Wang R. In vitro and in vivo characterization of opioid activities of endomorphins analogs with novel constrained C-terminus: evidence for the important role of proper spatial disposition of the third aromatic ring. Peptides 2007; 28:859-70. [PMID: 17276550 DOI: 10.1016/j.peptides.2007.01.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/24/2006] [Revised: 01/08/2007] [Accepted: 01/08/2007] [Indexed: 10/23/2022]
Abstract
In the present study, the C-terminus of endomorphin (Tyr(1)-Pro(2)-Trp/Phe(3)-Phe(4)-NH(2), EMs) analogs [Xaa(4)-R]EMs, modified by substitution of a non-aromatic residue for Phe(4) and ending up with -NH-benzyl, were designed to generate an atypical conformationally constrained peptide set. We investigated the effects of these analogs on the opioid receptors affinity, guinea pig ileum (GPI) and mouse vas deferens (MVD) activity, system arterial pressure (SAP), heart rate (HR), antinociception and colonic motility. Analogs 5 ([D-V(4)-Bzl]EM1) and 10 ([D-V(4)-Bzl]EM2), which exhibit appropriate spatial orientations of the third aromatic ring, were about 3-4 times more potent than their parents both in vivo and in vitro. However, a drastic loss of activity was found in analogs 2 ([A(4)-Bzl]EM1) and 7 ([A(4)-Bzl]EM2), which possess improper spatial orientations of the third aromatic ring. Interestingly, analog 7 or 3 ([G(4)-Bzl]EM1), when injected intravenously (i.v.), produced significantly different changes in SAP from their parents. Surprisingly, analog 4 displayed relatively higher vasodepressor activity but significantly less potent colonic contractile activity than analog 5. This may be elicited by the differences in the spatial disposition of the third aromatic ring, which were verified by molecular modeling. Our results indicate that the proper spatial disposition of the third aromatic ring plays an important role in the regulation of pharmacological activities of EMs.
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Affiliation(s)
- Ye Yu
- Institute of Biochemistry and Molecular Biology, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, China
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24
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Yu Y, Shao X, Cui Y, Liu HM, Wang CL, Fan YZ, Liu J, Dong SL, Cui YX, Wang R. Structure–Activity Study on the Spatial Arrangement of the Third Aromatic Ring of Endomorphins 1 and 2 Using an Atypical Constrained C Terminus. ChemMedChem 2007; 2:309-17. [PMID: 17285661 DOI: 10.1002/cmdc.200600274] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The discovery of endomorphins (EMs) has opened the possibility of searching for new analgesics. However, the design of peptide analgesics has proven to be very difficult as a result of their conformational flexibility and a lack of clarity in structure-activity relationships (SAR). In EMs, the amino acid side chains exhibit considerable conformational flexibility, especially in the third aromatic ring, which is free to adopt a bioactive conformation. To resolve these problems, a series of C terminus EM analogues, [Xaa(4)-R]EMs, modified through the substitution of Phe(4) with nonaromatic residues and termination with benzyl groups, were designed to generate conformational constrains of the third aromatic ring by amide bond and torsion angles (phi(4) and psi(4)) of Xaa(4). Introduction of (S)-alpha-methyl or (S)/(R)-alpha-carboxamide on the methylene unit of the benzyl group was designed to produce an atypical topographical constraint (phi(5)) of the third aromatic ring rotation. Interestingly, some EM derivatives, with elimination of the C-terminal carboxamide group and significant changes in the address sequence (Phe(4)-NH(2)), still exhibited higher mu-opioid receptor (MOR) affinity than unmodified EMs. In contrast, some analogues with incorrectly constrained C termini displayed very low affinity and pharmacological activities. Thus, our results indicate that these EM analogues, with atypical constrained C termini, provide model compounds with potent MOR agonism. They also give evidence that the proper spatial orientation and conformational restriction of the third aromatic ring are crucial for the interaction of EMs with MOR.
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Affiliation(s)
- Ye Yu
- Institute of Biochemistry and Molecular Biology, State Key Laboratory of Applied Organic Chemistry, Lanzhou University, 222 Tian Shui South Road, Lanzhou 730000, China
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25
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Sankararamakrishnan R. Recognition of GPCRs by Peptide Ligands and Membrane Compartments theory: Structural Studies of Endogenous Peptide Hormones in Membrane Environment. Biosci Rep 2006; 26:131-58. [PMID: 16773462 DOI: 10.1007/s10540-006-9014-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
One of the largest family of cell surface proteins, G-protein coupled receptors (GPCRs) regulate virtually all known physiological processes in mammals. With seven transmembrane segments, they respond to diverse range of extracellular stimuli and represent a major class of drug targets. Peptidergic GPCRs use endogenous peptides as ligands. To understand the mechanism of GPCR activation and rational drug design, knowledge of three-dimensional structure of receptor–ligand complex is important. The endogenous peptide hormones are often short, flexible and completely disordered in aqueous solution. According to “Membrane Compartments Theory”, the flexible peptide binds to the membrane in the first step before it recognizes its receptor and the membrane-induced conformation is postulated to bind to the receptor in the second step. Structures of several peptide hormones have been determined in membrane-mimetic medium. In these studies, micelles, reverse micelles and bicelles have been used to mimic the cell membrane environment. Recently, conformations of two peptide hormones have also been studied in receptor-bound form. Membrane environment induces stable secondary structures in flexible peptide ligands and membrane-induced peptide structures have been correlated with their bioactivity. Results of site-directed mutagenesis, spectroscopy and other experimental studies along with the conformations determined in membrane medium have been used to interpret the role of individual residues in the peptide ligand. Structural differences of membrane-bound peptides that belong to the same family but differ in selectivity are likely to explain the mechanism of receptor selectivity and specificity of the ligands. Knowledge of peptide 3D structures in membrane environment has potential applications in rational drug design.
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26
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Abel S, Waks M, Urbach W, Marchi M. Structure, Stability, and Hydration of a Polypeptide in AOT Reverse Micelles. J Am Chem Soc 2005; 128:382-3. [PMID: 16402804 DOI: 10.1021/ja053043u] [Citation(s) in RCA: 40] [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
In this communication, we provide theoretical evidence that the folded structure of a simple peptide, alanine zwitterionic octapeptide, or A8, unstable in solution, becomes stable in a reverse micelle (RM) of appropriate size. Our molecular dynamics simulations were carried out for realistic models of sodium 2-ethylhexylsulfosuccinate RM in isooctane, simulated for an extended period of time. For the RM of the smaller size, we find that a helical structure is stable for the whole length of the simulation. On the contrary, the peptide very quickly takes an extended structure in larger micelles.
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Affiliation(s)
- Stéphane Abel
- Commissariat à l'Energie Atomique, DSV-DBJC-SBFM, Centre d'Etudes, Saclay, Gif-sur-Yvette, France
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27
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In Y, Minoura K, Tomoo K, Sasaki Y, Lazarus LH, Okada Y, Ishida T. Structural function of C-terminal amidation of endomorphin. FEBS J 2005; 272:5079-97. [PMID: 16176278 DOI: 10.1111/j.1742-4658.2005.04919.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
To investigate the structural function of the C-terminal amide group of endomorphin-2 (EM2, H-Tyr-Pro-Phe-Phe-NH(2)), an endogenous micro-opioid receptor ligand, the solution conformations of EM2 and its C-terminal free acid (EM2OH, H-Tyr-Pro-Phe-Phe-OH) in TFE (trifluoroethanol), water (pH 2.7 and 5.2), and aqueous DPC (dodecylphosphocholine) micelles (pH 3.5 and 5.2) were investigated by the combination of 2D (1)H-NMR measurement and molecular modelling calculation. Both peptides were in equilibrium between the cis and trans rotamers around the Tyr--Pro w bond with population ratios of 1 : 1 to 1 : 2 in dimethyl sulfoxide, TFE and water, whereas they predominantly took the trans rotamer in DPC micelle, except in EM2OH at pH 5.2, which had a trans/cis rotamer ratio of 2 : 1. Fifty possible 3D conformers were generated for each peptide, taking different electronic states depending on the type of solvent and pH (neutral and monocationic forms for EM2, and zwitterionic and monocation forms for EM2OH) by the dynamical simulated annealing method, under the proton-proton distance constraints derived from the ROE cross-peak intensities. These conformers were then roughly classified into four groups of two open [reverse S (rS)- and numerical 7 (n7)-type] and two folded (F1- and F2-type) conformers according to the conformational pattern of the backbone structure. Most EM2 conformers in neutral (in TFE) and monocationic (in water and DPC micelles) forms adopted the open structure (mixture of major rS-type and minor n7-type conformers) despite the trans/cis rotamer form. On the other hand, the zwitterionic EM2OH in TFE, water and DPC micelles showed an increased population of F1- and F2-type folded conformers, the population of which varied depending on their electronic state and pH. Most of these folded conformers took an F1-type structure similar to that stabilized by an intramolecular hydrogen bond of (Tyr1)NH(3) (+)...COO(-)(Phe4), observed in its crystal structure. These results show that the substitution of a carboxyl group for the C-terminal amide group makes the peptide structure more flexible and leads to the ensemble of folded and open conformers. The conformational requirement of EM2 for binding to the micro-opioid receptor and the structural function of the C-terminal amide group are discussed on the basis of the present conformational features of EM2 and EM2OH and a possible model for binding to the micro-opioid receptor, constructed from the template structure of rhodopsin.
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Affiliation(s)
- Yasuko In
- Osaka University of Pharmaceutical Sciences, Takatsuki, Osaka, Japan.
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28
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Leitgeb B, Tóth G. Aromatic–aromatic and proline–aromatic interactions in endomorphin-1 and endomorphin-2. Eur J Med Chem 2005; 40:674-86. [PMID: 15935902 DOI: 10.1016/j.ejmech.2004.10.015] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2004] [Revised: 10/21/2004] [Accepted: 10/21/2004] [Indexed: 11/23/2022]
Abstract
We investigated the aromatic-aromatic and proline-aromatic interactions in endomorphin-1 and endomorphin-2, and different types of these interactions were observed. For all the interacting pairs, the preferred geometric orientations were identified. We examined these interactions in the preferred secondary structures, which are different types of beta-turns and gamma-turns. These results revealed that the majority of the turn structures contained one of the interacting aromatic-aromatic or proline-aromatic pairs. On the basis of our results, it can be assumed that these interactions may be important in the determination and stabilization of the structures of endomorphins. Furthermore, our observations suggest that a conformation stabilized by an aromatic-aromatic or proline-aromatic interaction can play an important role in the association with the receptor.
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Affiliation(s)
- Balázs Leitgeb
- Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Temesvári krt. 62, H-6726 Szeged, Hungary.
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29
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Grieco P, Giusti L, Carotenuto A, Campiglia P, Calderone V, Lama T, Gomez-Monterrey I, Tartaro G, Mazzoni MR, Novellino E. Morphiceptin Analogues Containing a Dipeptide Mimetic Structure: An Investigation on the Bioactive Topology at the μ-Receptor. J Med Chem 2005; 48:3153-63. [PMID: 15857121 DOI: 10.1021/jm040867y] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We describe the design, the conformational behavior, and the biological activity at the mu-opioid receptor of new morphiceptin analogues. In these analogues a recently described dipeptide mimetic structure replaces both the N- and the C-terminal Xaa-Pro dipeptide of morphiceptin. Conformational investigation on the most active analogue, compared to the parent peptide, indicates a high degree of structural tolerance within the mu-opioid receptor binding site. In fact, our results indicate that only the location and the relative orientation of the side chains of the aromatic pharmacophoric residues represent the indispensable structural features for mu-receptor binding. To reach such topological arrangement, opioid peptides can adopt different conformations and configurations. In particular, opioid peptides bearing a proline residue as spacer between the two aromatic residues can adopt, in the active state, both cis and trans configurations at the Tyr(1)-Pro(2) amide bond, each of them with the appropriate backbone and side chains orientations.
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Affiliation(s)
- Paolo Grieco
- Dipartimento di Chimica Farmaceutica e Tossicologica, Università degli Studi di Napoli "Federico II", I-80131 Napoli, Italy
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30
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Vincent M, de Foresta B, Gallay J. Nanosecond dynamics of a mimicked membrane-water interface observed by time-resolved stokes shift of LAURDAN. Biophys J 2005; 88:4337-50. [PMID: 15778437 PMCID: PMC1305662 DOI: 10.1529/biophysj.104.057497] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We studied the dipolar relaxation of the surfactant-water interface in reverse micelles of AOT-water in isooctane in the nanosecond and subnanosecond time ranges by incorporating the amphipathic solvatochromic fluorescent probes LAURDAN and TOE. A negative component was observed in the fluorescence decays in the red edge of the emission spectrum-the signature of an excited state reaction-with LAURDAN but not for TOE. The deconvolution of the transient reconstructed spectra of LAURDAN based on a model constructed by adding together three log-normal Gaussian equations made it possible to separate the specific dynamic solvent response from the intramolecular excited state reactions of the probe. The deconvoluted spectrum of lowest energy displayed the largest Stokes shift. This spectral shift was described by unimodal kinetics on the nanosecond timescale, whereas the relaxation kinetics of water-soluble probes have been reported to be biphasic (on the subnanosecond and nanosecond timescales) due to the heterogeneous distribution of these probes in the water pool. Most of this spectral shift probably resulted from water relaxation as it was highly sensitive to the water to surfactant molar ratio (w(0)) (60-65 nm at w(0) = 20-30). A small part of this spectral shift (9 nm at w(0) = 0) probably resulted from dipolar interaction with the AOT polar headgroup. The measured relaxation time values were in the range of the rotational motion of the AOT polar headgroup region as assessed by LAURDAN and TOE fluorescence anisotropy decays.
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Affiliation(s)
- Michel Vincent
- LURE Laboratoire pour l'Utilisation du Rayonnement Electromagnétique, Université Paris-Sud, Bâtiment 209D, Orsay, France
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31
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Renner C, Fiori S, Fiorino F, Landgraf D, Deluca D, Mentler M, Grantner K, Parak FG, Kretzschmar H, Moroder L. Micellar environments induce structuring of the N-terminal tail of the prion protein. Biopolymers 2004; 73:421-33. [PMID: 14991659 DOI: 10.1002/bip.20015] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In the physiological form, the prion protein is a glycoprotein tethered to the cell surface via a C-terminal glycosylphosphatidylinositol anchor, consisting of a largely alpha-helical globular C-terminal domain and an unstructured N-terminal portion. This unstructured part of the protein contains four successive octapeptide repeats, which were shown to bind up to four Cu(2+) ions in a cooperative manner. To mimic the location of the protein on the cell membrane and to analyze possible structuring effects of the lipid/water interface, the conformational preferences of a single octapeptide repeat and its tetrameric form, as well of the fragment 92-113, proposed as an additional copper binding site, were comparatively analyzed in aqueous and dodecylphosphocholine micellar solution as a membrane mimetic. While for the downstream fragment 92-113 no conformational effects were detectable in the presence of DPC micelles by CD and NMR, both the single octapeptide repeat and, in an even more pronounced manner, its tetrameric form are restricted into well-defined conformations. Because of the repetitive character of the rigid structural subdomain in the tetrarepeat molecule, the spatial arrangement of these identical motifs could not be resolved by NMR analysis. However, the polyvalent nature of the repetitive subunits leads to a remarkably enhanced interaction with the micelles, which is not detectably affected by copper complexation. These results strongly suggest interactions of the cellular form of PrP (PrP(c)) N-terminal tail with the cell membrane surface at least in the octapeptide repeat region with preorganization of these sequence portions for copper complexation. There are sufficient experimental facts known that support a physiological role of copper complexation by the octapeptide repeat region of PrP(c) such as a copper-buffering role of the PrP(c) protein on the extracellular surface.
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32
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Tömböly C, Kövér KE, Péter A, Tourwé D, Biyashev D, Benyhe S, Borsodi A, Al-Khrasani M, Rónai AZ, Tóth G. Structure−Activity Study on the Phe Side Chain Arrangement of Endomorphins Using Conformationally Constrained Analogues. J Med Chem 2003; 47:735-43. [PMID: 14736254 DOI: 10.1021/jm0310028] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Endomorphins-1 and -2 were substituted with all the beta-MePhe stereoisomers in their Phe residues to generate a conformationally constrained peptide set. This series of molecules was subjected to biological assays, and for beta-MePhe(4)-endomorphins-2, a conformational analysis was performed. Incorporation of (2S,3S)-beta-MePhe(4) resulted in the most potent analogues of both endomorphins with enhanced enzymatic stability. Their micro opioid affinities were 4-times higher than the parent peptides, they stimulated [(35)S]GTPgammaS binding, and they were found to be full agonists. NMR experiments revealed that C-terminal (2S,3S)-beta-MePhe in endomorphin-2 strongly favored the gauche (-) spatial orientation which implies the presence of the chi(1) = -60 degrees rotamer of Phe(4) in the binding conformer of endomorphins. Our results emphasize that the appropriate orientation of the C-terminal aromatic side chain of endomorphins is substantial for binding to the micro opioid receptor.
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Affiliation(s)
- Csaba Tömböly
- Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, 6701 Szeged, P.O. Box 521, Hungary
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33
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Ötvös F, Körtvélyesi T, Tóth G. Structure-activity relationships of endomorphin-1, endomorphin-2 and morphiceptin by molecular dynamics methods. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/j.theochem.2003.08.044] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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34
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Leitgeb B, Szekeres A. Exploring the conformational space of the μ-opioid agonists endomorphin-1 and endomorphin-2. ACTA ACUST UNITED AC 2003. [DOI: 10.1016/j.theochem.2003.08.043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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35
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Leitgeb B, Szekeres A, Tóth G. Conformational analysis of endomorphin-1 by molecular dynamics methods. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2003; 62:145-57. [PMID: 12969194 DOI: 10.1034/j.1399-3011.2003.00084.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Endomorphin-1 (EM1, H-Tyr-Pro-Trp-Phe-NH2) is a highly potent and selective agonist for the mu-opioid receptor. A conformational analysis of this tetrapeptide was carried out by simulated annealing and molecular dynamics methods. EM1 was modeled in the neutral (NH2-) and cationic (NH-) forms of the N-terminal amino group. The results of NMR measurements were utilized to perform simulations with restrained cis and trans Tyr1-Pro2 peptide bonds. Preferred conformational regions in the Phi 2-Psi 2, Phi 3-Psi 3 and Phi 4-Psi 4 Ramachandran plots were identified. The g(+), g(-) and trans rotamer populations of the side-chains of the Tyr1, Trp3 and Phe4 residues were determined in chi 1 space. The distances between the N-terminal N atom and the other backbone N and O atoms, and the distances between the centers of the aromatic side-chain rings and the Pro2 ring were measured. The preferred secondary structures were determined as different types of beta-turns and gamma-turns. In the conformers of trans-EM1, an inverse gamma-turn can be formed in the N-terminal region, but in the conformers of cis-EM1 the N-terminal inverse gamma-turn is absent. Regular and inverse gamma-turns were observed in the C-terminal region in both isomers. These beta- and gamma-turns were stabilized by intramolecular H-bonds and bifurcated H-bonds.
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Affiliation(s)
- B Leitgeb
- Institute of Biochemistry, Biological Research Center of the Hungarian Academy of Sciences, Szeged, Hungary
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36
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Marcotte I, Dufourc EJ, Ouellet M, Auger M. Interaction of the neuropeptide met-enkephalin with zwitterionic and negatively charged bicelles as viewed by 31P and 2H solid-state NMR. Biophys J 2003; 85:328-39. [PMID: 12829487 PMCID: PMC1303088 DOI: 10.1016/s0006-3495(03)74477-4] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
The interaction of the neuropeptide methionine-enkephalin (Menk) with bicelles was investigated by solid-state NMR. Bicelles composed of dimyristoylphosphatidylcholine (DMPC) and dicaproylphosphatidylcholine (DCPC) were modified to investigate the effect of the lipid headgroup and electrostatic charges on the association with Menk. A total of 10 mol % of DMPC was replaced by zwitterionic phosphatidylethanolamine (DMPE), anionic phosphatidylglycerol (DMPG), or phosphatidylserine (DMPS). The preparation of DMPE-doped bicelles (Bic/PE) is reported for the first time. The (31)P and (2)H NMR results revealed changes in the lipid dynamics when Menk interacts with the bicellar systems. (2)H NMR experiments showed a disordering effect of Menk on the lipid chains in all the bicelles except Bic/PG, whereas the study of the choline headgroups indicated a decreased order of the lipids only in Bic/PE and Bic/PG. Our results suggest that the insertion depth of Menk into bicelles is modulated by their composition, more specifically by the balance between hydrophobic and electrostatic interactions. Menk would be buried at the lipid polar/apolar interface, the depth of penetration into the hydrophobic membrane core following the scaling Bic > Bic/PE > Bic/PS at the slightly acidic pH used in this study. The peptide would not insert into the bilayer core of Bic/PG and would rather remain at the surface.
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Affiliation(s)
- Isabelle Marcotte
- Département de Chimie, Centre de Recherche en Sciences et Ingénierie des Macromolécules, Université Laval, Québec, Québec, Canada, G1K 7P4
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37
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Cardillo G, Gentilucci L, Tolomelli A, Qasem AR, Spampinato S, Calienni M. Conformational analysis and μ-opioid receptor affinity of short peptides, endomorphin models in a low polarity solvent. Org Biomol Chem 2003; 1:3010-4. [PMID: 14518122 DOI: 10.1039/b306161m] [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: 11/21/2022]
Abstract
Peptide carbamates containing the sequence H-Pro-Trp-PheNH2 showed in CDCl3 restricted conformations stabilized by the presence of a gamma-turn. To test the reliability of the peptides as endomorphin conformational models, we measured the affinities for mu-receptors labelled with [3H]-DAMGO. In particular, Cbz-Pro-Trp-PheNH2 displayed a nanomolar affinity.
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Affiliation(s)
- Giuliana Cardillo
- Dipartimento di Chimica G. Ciamician, C.S.F.M., Università di Bologna, via Selmi 2, 40126-Bologna, Italy.
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38
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Doi M, Asano A, Komura E, Ueda Y. The structure of an endomorphin analogue incorporating 1-aminocyclohexane-1-carboxlylic acid for proline is similar to the beta-turn of Leu-enkephalin. Biochem Biophys Res Commun 2002; 297:138-42. [PMID: 12220521 DOI: 10.1016/s0006-291x(02)02087-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Endomorphin (EM2, Tyr-Pro-Phe-Phe-NH(2)) can assume various conformations related to cis/trans-rotamers of the amide linkage of Tyr-Pro. To control isomerization, restricted or flexible components have been introduced at the Pro position. We focused on [Chx(2)]EM2, an EM2 analogue substituting 1-aminocyclohexane-1-carboxlylic acid (Chx) for Pro. X-ray diffraction analysis revealed that [Chx(2)]EM2 is folded into the trans-form of Tyr-Chx. The manner of folding resembled that seen in D-TIPP, an EM analogue incorporating tetrahydroisoquinoline carboxylic acid, as well as the beta-turn of Leu-enkephalin. Selectivity for the opioid mu-receptor was fairly well conserved by [Chx(2)]EM, suggesting that the folded form is important for mu-selectivity.
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Affiliation(s)
- Mitsunobu Doi
- Osaka University of Pharmaceutical Sciences, 4-20-1 Nasahara, Takatsuki, Osaka 569-1094, Japan.
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39
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Amodeo P, Guerrini R, Picone D, Salvadori S, Spadaccini R, Tancredi T, Temussi PA. Solution structure of nociceptin peptides. J Pept Sci 2002; 8:497-509. [PMID: 12371703 DOI: 10.1002/psc.412] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2002] [Accepted: 05/14/2002] [Indexed: 11/10/2022]
Abstract
Peptides embedded in the sequence of pre-pro-nociceptin, i.e. nociceptin, nocistatin and orphanin FQ2, have shed light on the complexity of the mechanisms involving the peptide hormones related to pain and have opened up new perspectives for the clinical treatment of pain. The design of new ligands with high selectivity and bioavailability, in particular for ORL1, is important both for the elucidation and control of the physiological role of the receptor and for their therapeutic importance. The failure to obtain agonists and antagonists when using, for nociceptin, the same substitutions that are successful for opioids, and the conformational flexibility of them all, justify systematic efforts to study the solution conformation under conditions as close as possible to their natural environment. Structural studies of linear peptides in solution are hampered by their high flexibility. A direct structural study of the complex between a peptide and its receptor would overcome this difficulty, but such a study is not easy since opioid receptors are membrane proteins. Thus, conformational studies of lead peptides in solution are still important for drug design. This review deals with conformational studies of natural pre-nociceptin peptides in several solvents that mimic in part the different environments in which the peptides exert their action. None of the structural investigations yielded a completely reliable bioactive conformation, but the global conformation of the peptides in biomimetic environments can shed light on their interaction with receptors.
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Affiliation(s)
- Pietro Amodeo
- Istituto di Chimica Biomolecolare del CNR, Pozzuoli, Italy
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40
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Cardillo G, Gentilucci L, Qasem AR, Sgarzi F, Spampinato S. Endomorphin-1 analogues containing beta-proline are mu-opioid receptor agonists and display enhanced enzymatic hydrolysis resistance. J Med Chem 2002; 45:2571-8. [PMID: 12036366 DOI: 10.1021/jm011059z] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
In this paper we describe the synthesis and affinity toward the mu-opioid receptor of some tetrapeptides obtained from endomorphin-1, H-Tyr-Pro-Trp-Phe-NH(2) (1), by substituting each amino acid in turn with its homologue. The ability to bind mu-opioid receptors depends on the beta-amino acid, and in particular 4, which contains beta-L-Pro, has a K(I) in the nanomolar range. The peptides 4 and 5 are significantly more resistant to enzymatic hydrolysis than 1. The same compounds, as well as the mu-opioid receptor agonist DAMGO, produced a concentration-dependent inhibition of forskolin-stimulated cyclic AMP formation, thus behaving as mu-opioid agonists. These features suggest that this novel class of endomorphin-1 analogues may represent suitable candidates for the in vivo investigation as potential mu-opioid receptor agonists.
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Affiliation(s)
- Giuliana Cardillo
- Dipartimento di Chimica G. Ciamician, via Selmi 2, Università degli Studi di Bologna, 40126-Bologna, Italy
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41
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Lengyel I, Orosz G, Biyashev D, Kocsis L, Al-Khrasani M, Rónai A, Tömböly C, Fürst Z, Tóth G, Borsodi A. Side chain modifications change the binding and agonist properties of endomorphin 2. Biochem Biophys Res Commun 2002; 290:153-61. [PMID: 11779147 DOI: 10.1006/bbrc.2001.6136] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Side chain modifications were introduced to endomorphin 2 (E2) to improve its binding properties and biological activity. A number of C-terminal modifications decreased the binding affinity to the mu-opioid receptor and the intrinsic activity in rat brain membranes. The exception was E2-ol, which showed increased binding affinity to MOR and higher potency in stimulating [(35)S]GTPgammaS binding. N-methylation of Phe(3) (MePhe(3)) attenuated the binding affinity and produced a rightward shift of [(35)S]GTPgammaS binding curves. All derivatives had lower intrinsic activity than E2. Some of the modified peptides partially inhibited, while YPF-benzyl-allyl-amide fully inhibited, the E2 or [d-Ala(2),MePhe(4),Gly(5)ol]enkephalin stimulated [(35)S]GTPgammaS binding. Marked differences were found between the results obtained using tritiated E2, tritiated naloxone, and [(35)S]GTPgammaS binding, indicating the possible involvement of multiple binding sites. The data presented demonstrate that the C-terminal amide group has an essential role in the regulation of the binding and the agonist/antagonist properties of E2.
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Affiliation(s)
- I Lengyel
- Institute of Biochemistry, Biological Research Centre, Hungarian Academy of Sciences, P.O. Box 521, H-6701 Szeged, Hungary.
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Keller M, Boissard C, Patiny L, Chung NN, Lemieux C, Mutter M, Schiller PW. Pseudoproline-containing analogues of morphiceptin and endomorphin-2: evidence for a cis Tyr-Pro amide bond in the bioactive conformation. J Med Chem 2001; 44:3896-903. [PMID: 11689075 DOI: 10.1021/jm000332e] [Citation(s) in RCA: 80] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Analogues of the opioid peptides [D-Phe(3)]morphiceptin (H-Tyr-Pro-D-Phe-Pro-NH(2)) and endomorphin-2 (H-Tyr-Pro-Phe-Phe-NH(2)) containing the pseudoproline (Psi Pro) (4R)-thiazolidine-4-carboxylic acid (Cys[Psi(R1,R2)pro]) or (4S)-oxazolidine-4-carboxylic acid (Ser[Psi(R1,R2)pro]) in place of Pro(2) were synthesized. The pseudoproline ring in these compounds was either unsubstituted (R(1), R(2) = H) or dimethylated (R(1), R(2) = CH(3)) at the 2-C position. 2-C-dimethylated pseudoprolines are known to be quantitative or nearly quantitative inducers of the cis conformation around the Xaa(i-1)-Xaa(i)[Psi(CH(3),CH)(3)pro)] imide bond. All dihydropseudoproline-containing analogues (R(1), R(2) = H) showed good mu opioid agonist potency in the guinea pig ileum (GPI) assay, high mu receptor binding affinity in the rat brain membrane binding assay, and, like their parent peptides, excellent mu receptor binding selectivity. (1)H NMR spectroscopic analysis of the Cys[Psi(H,H)pro](2)- and Ser[Psi(H,H)pro](2)-containing analogues in DMSO-d(6) revealed that they existed in a conformational equilibrium around the Tyr-Xaa[Psi(H,H)pro] peptide bond with cis/trans ratios of 40:60 and 45:55, respectively. The dimethylated thiazolidine- and oxazolidine-containing [D-Phe(3)]morphiceptin- and endomorphin-2 analogues (R(1), R(2) = CH(3)) all retained full mu agonist potency in the GPI assay and displayed mu receptor binding affinities in the nanomolar range and high mu receptor selectivity. As expected, no conformers of the latter analogues with a trans conformation around the Tyr-Xaa[Psi(CH(3),CH(3)pro)] imide bond were detected by (1)H NMR spectral analysis, indicating that in these compounds the cis conformation is highly predominant (>98%). These results represent the most direct evidence obtained so far to indicate that morphiceptin and endomorphin-2 have the cis conformation around the Tyr-Pro peptide bond in their bioactive conformations.
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Affiliation(s)
- M Keller
- Institute of Organic Chemistry, BCH-Dorigny, University of Lausanne, CH-1015 Lausanne, Switzerland
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43
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In Y, Minoura K, Ohishi H, Minakata H, Kamigauchi M, Sugiura M, Ishida T. Conformational comparison of mu-selective endomorphin-2 with its C-terminal free acid in DMSO solution, by 1H NMR spectroscopy and molecular modeling calculation. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2001; 58:399-412. [PMID: 11892849 DOI: 10.1034/j.1399-3011.2001.00891.x] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
In order to make clear the structural role of the C-terminal amide group of endomorphin-2 (EM2, H-Tyr-Pro-Phe-Phe-NH2), an endogenous mu-receptor ligand, in the biological function, the solution conformations of endomorphin-2 and its C-terminal free acid (EM2OH, H-Tyr-Pro-Phe-Phe-OH), studied using two-dimensional 1H NMR measurements and molecular modeling calculations, were compared. Both peptides were in equilibrium between the cis and trans isomers around the Tyr-Pro omega bond in a population ratio of approximately/= 1:2. The lack of significant temperature and concentration dependence of NH protons suggested that the NMR spectra reflected the conformational features of the respective molecules themselves. Fifty possible 3D structures for the each isomer were generated by the dynamical simulated annealing method under the proton-proton distance constraints derived from the ROE cross-peaks. These energy-minimized conformers, which were all in the phi torsion angles estimated from J(NHCalphaH) coupling constants within +/- 30 degrees, were then classified in groups one or two according to the folding backbone structures. All trans and cis EM2 conformers adopt an open conformation in which their extended backbone structures are twisted at the Pro2-Phe3 moiety. In contrast, the trans and cis conformers of EM2OH show conformational variation between the 'bow'-shaped extended and folded backbone structures, although the cis conformers of its zwitterionic form are refined into the folded structure of the close disposition of C- and N-terminal groups. These results indicate clearly that the substitution of carboxyl group for C-terminal amide group makes the peptide flexible. The conformational requirement for mu-receptor activation has been discussed based on the active form proposed for endomorphin-1 and by comparing conformational features of EM2 and EM2OH.
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Affiliation(s)
- Y In
- Department of Physical Chemistry, Osaka University of Pharmaceutical Sciences, Takatsuki, Japan.
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44
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45
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Metzler DE, Metzler CM, Sauke DJ. Chemical Communication Between Cells. Biochemistry 2001. [DOI: 10.1016/b978-012492543-4/50033-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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46
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Horvath G. Endomorphin-1 and endomorphin-2: pharmacology of the selective endogenous mu-opioid receptor agonists. Pharmacol Ther 2000; 88:437-63. [PMID: 11337033 DOI: 10.1016/s0163-7258(00)00100-5] [Citation(s) in RCA: 100] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The recently discovered endogenous opioid peptides, endomorphins-1 and -2, appear to have properties consistent with neurotransmitter/neuromodulator actions in mammals. This review surveys the information gained so far from studies of different aspects of the endomorphins. Thus, the endomorphins have been found unequally in the brain; they are stored in neurons and axon terminals, with a heterogeneous distribution; they are released from synaptosomes by depolarization; they are enzymatically converted by endopeptidases; and they interact specifically and with high affinity with mu-opioid receptors. The most outstanding effect of the endomorphins is their antinociceptive action. This depends on both central and peripheral neurons. Additionally, the endomorphins cause vasodilatation by stimulating nitric oxide release from the endothelium. Their roles in different central and peripheral functions, however, have not been fully clarified yet. From a therapeutic perspective, therefore, they may be conceived at present as potent antinociceptive and vasodilator agents.
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Affiliation(s)
- G Horvath
- Department of Physiology, Faculty of Medicine and Faculty of Health Sciences, University of Szeged, P.O. Box 427, H-6701, Szeged, Hungary.
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