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Sarojini V, Cameron AJ, Varnava KG, Denny WA, Sanjayan G. Cyclic Tetrapeptides from Nature and Design: A Review of Synthetic Methodologies, Structure, and Function. Chem Rev 2019; 119:10318-10359. [PMID: 31418274 DOI: 10.1021/acs.chemrev.8b00737] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Small cyclic peptides possess a wide range of biological properties and unique structures that make them attractive to scientists working in a range of areas from medicinal to materials chemistry. However, cyclic tetrapeptides (CTPs), which are important members of this family, are notoriously difficult to synthesize. Various synthetic methodologies have been developed that enable access to natural product CTPs and their rationally designed synthetic analogues having novel molecular structures. These methodologies include the use of reversible protecting groups such as pseudoprolines that restrict conformational freedom, ring contraction strategies, on-resin cyclization approaches, and optimization of coupling reagents and reaction conditions such as temperature and dilution factors. Several fundamental studies have documented the impacts of amino acid configurations, N-alkylation, and steric bulk on both synthetic success and ensuing conformations. Carefully executed retrosynthetic ring dissection and the unique structural features of the linear precursor sequences that result from the ring dissection are crucial for the success of the cyclization step. Other factors that influence the outcome of the cyclization step include reaction temperature, solvent, reagents used as well as dilution levels. The purpose of this review is to highlight the current state of affairs on naturally occurring and rationally designed cyclic tetrapeptides, including strategies investigated for their syntheses in the literature, the conformations adopted by these molecules, and specific examples of their function. Using selected examples from the literature, an in-depth discussion of the synthetic techniques and reaction parameters applied for the successful syntheses of 12-, 13-, and 14-membered natural product CTPs and their novel analogues are presented, with particular focus on the cyclization step. Selected examples of the three-dimensional structures of cyclic tetrapeptides studied by NMR, and X-ray crystallography are also included.
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Affiliation(s)
- Vijayalekshmi Sarojini
- School of Chemical Sciences and the Centre for Green Chemical Science , University of Auckland , Auckland 1142 , New Zealand.,The MacDiarmid Institute for Advanced Materials and Nanotechnology , Wellington 6140 , New Zealand
| | - Alan J Cameron
- School of Chemical Sciences and the Centre for Green Chemical Science , University of Auckland , Auckland 1142 , New Zealand
| | - Kyriakos G Varnava
- School of Chemical Sciences and the Centre for Green Chemical Science , University of Auckland , Auckland 1142 , New Zealand
| | | | - Gangadhar Sanjayan
- Division of Organic Chemistry , CSIR-National Chemical Laboratory , Dr. Homi Bhabha Road , Pune 411 008 , India
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2
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Slough DP, McHugh SM, Lin YS. Understanding and designing head-to-tail cyclic peptides. Biopolymers 2018; 109:e23113. [PMID: 29528114 PMCID: PMC6135719 DOI: 10.1002/bip.23113] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2017] [Revised: 02/23/2018] [Accepted: 02/26/2018] [Indexed: 01/30/2023]
Abstract
Cyclic peptides (CPs) are an exciting class of molecules with a variety of applications. However, design strategies for CP therapeutics, for example, are generally limited by a poor understanding of their sequence-structure relationships. This knowledge gap often leads to a trial-and-error approach for designing CPs for a specific purpose, which is both costly and time-consuming. Herein, we describe the current experimental and computational efforts in understanding and designing head-to-tail CPs along with their respective challenges. In addition, we provide several future directions in the field of computational CP design to improve its accuracy, efficiency and applicability. These advances, combined with experimental techniques, shall ultimately provide a better understanding of these interesting molecules and a reliable working platform to rationally design CPs with desired characteristics.
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Affiliation(s)
| | | | - Yu-Shan Lin
- Department of Chemistry, Tufts University, Medford, Massachusetts, 02155, United States
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3
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Moussodia RO, Acherar S, Romero E, Didierjean C, Jamart-Grégoire B. Evidence of Nanotubular Self-Organization in Solution and Solid States of Heterochiral Cyclo 1:1 [α/α-Nα-Bn-hydrazino]mers Series. J Org Chem 2015; 80:3022-9. [DOI: 10.1021/jo502684g] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Affiliation(s)
- Ralph-Olivier Moussodia
- Laboratoire
de Chimie Physique Macromoléculaire (LCPM), Université de Lorraine-CNRS, UMR 7375, 1 rue Grandville, BP 20451, 54001 Nancy cedex, France
| | - Samir Acherar
- Laboratoire
de Chimie Physique Macromoléculaire (LCPM), Université de Lorraine-CNRS, UMR 7375, 1 rue Grandville, BP 20451, 54001 Nancy cedex, France
| | - Eugénie Romero
- Laboratoire
de Chimie Physique Macromoléculaire (LCPM), Université de Lorraine-CNRS, UMR 7375, 1 rue Grandville, BP 20451, 54001 Nancy cedex, France
| | - Claude Didierjean
- Laboratoire de Crystallographie, Résonance Magnétique
et Modélisations (CRM2), Université de Lorraine-CNRS, UMR 7036, Faculté des Sciences et Technologies, BP 20239, 54506 Vandœuvre-lès-Nancy cedex, France
| | - Brigitte Jamart-Grégoire
- Laboratoire
de Chimie Physique Macromoléculaire (LCPM), Université de Lorraine-CNRS, UMR 7375, 1 rue Grandville, BP 20451, 54001 Nancy cedex, France
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4
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Oakley MT, Oheix E, Peacock AFA, Johnston RL. Computational and Experimental Investigations into the Conformations of Cyclic Tetra-α/β-peptides. J Phys Chem B 2013; 117:8122-34. [DOI: 10.1021/jp4043039] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Mark T. Oakley
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K
| | - Emmanuel Oheix
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K
| | - Anna F. A. Peacock
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K
| | - Roy L. Johnston
- School of Chemistry, University of Birmingham, Edgbaston, Birmingham, B15 2TT, U.K
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5
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Caumes C, Fernandes C, Roy O, Hjelmgaard T, Wenger E, Didierjean C, Taillefumier C, Faure S. Cyclic α,β-tetrapeptoids: sequence-dependent cyclization and conformational preference. Org Lett 2013; 15:3626-9. [PMID: 23806006 DOI: 10.1021/ol401478j] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
The presence of at least one N-Cα branched side chain is crucial for successful cyclization of α,β-tetrapeptoids. The ctct amide sequence revealed in the crystal structure of the 14-membered cyclotetrapeptoid 8 is also the most populated conformation in solution and is reminiscent of the predominant amide arrangement of the 12-membered cyclic tetrapeptides (CTPs).
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Affiliation(s)
- Cécile Caumes
- Clermont Université, Université Blaise Pascal, Institut de Chimie de Clermont-Ferrand, BP10448, F-63000 Clermont-Ferrand, France
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6
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Vass E, Majer Z, Kőhalmy K, Hollósi M. Vibrational and chiroptical spectroscopic characterization of γ-turn model cyclic tetrapeptides containing two β-Ala residues. Chirality 2010; 22:762-71. [DOI: 10.1002/chir.20831] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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7
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Jeremic T, Linden A, Moehle K, Heimgartner H. Synthesis and conformational analysis of 18-membered Aib-containing cyclohexapeptides. Tetrahedron 2005. [DOI: 10.1016/j.tet.2004.12.012] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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8
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Seebach D, Bezençon O, Jaun B, Pietzonka T, Matthews JL, Kühnle FNM, Schweizer WB. FurtherC-Alkylations of CyclotetrapeptidesviaLithium and Phosphazenium (P4) Enolates: Discovery of a New Conformation. Helv Chim Acta 2004. [DOI: 10.1002/hlca.19960790303] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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9
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Bhadbhade MM, Kishore R. An observation of non-superimposable stereogeometrical features in a non-chiral one-component β-Ala model peptide. Biochem Biophys Res Commun 2004; 316:1029-36. [PMID: 15044088 DOI: 10.1016/j.bbrc.2004.02.152] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2004] [Indexed: 10/26/2022]
Abstract
This paper describes the chemical synthesis and crystal molecular conformation of a non-chiral beta-Ala containing model peptide Boc-beta-Ala-Acc5-OCH3. The analysis revealed the existence of two crystallographically independent molecules A and B, in the asymmetric unit. Unexpectedly, while the magnitudes of the backbone torsion angles in both molecules are remarkably similar, the signs of the corresponding torsion angles are reverse therefore, inclining us to suggest the existence of non-superimposable stereogeometrical features in a non-chiral one-component beta-Ala model system. The critical mu torsion angle around CbetaH2-CalphaH2 bond of the beta-Ala residue represents a typical gauche orientation i.e., mu = 67.7 degrees in A and mu = -61.2 degrees in B, providing the molecule an overall crescent shaped topology. The observed conformation contrasts markedly to those determined for the correlated non-chiral model peptides: Boc-beta-Ala-Acc6-OCH3 and Boc-beta-Ala-Aib-OCH3 signifying the role of stereocontrolling elements since the stereochemically constrained Calpha, alpha-disubstituted glycyl residues (e.g., Acc5, Acc6, and the prototype Aib) are known to strongly restrict the peptide backbone conformations in the 3(10)/alpha-helical-regions ( phi approximately +/-60+/-20 degrees, psi approximately +/-30+/-20 degrees) of the Ramachandran map. Unpredictably, the preferred, phi, psi torsion angles of the Acc5 residue fall outside the helical regions of the Ramachandran map and exhibit opposite-handed twists for A and B. The implications of the semi-extended conformation of the Acc5 residue in the construction of backbone-modified novel scaffolds and peptides of biological relevance are highlighted. Taken together, the results indicate that in short linear beta-Ala containing peptides specific structural changes can be induced by selective substitution of non-coded linear- or cyclic symmetrically Calpha,alpha-disubstituted glycines, reinstating the hypothesis that in addition to conformational restrictions, the chemical nature of the neighboring side-chain substituents and local environments collectively influences the stabilization of folding-unfolding behavior of the two methylene units of a beta-Ala residue.
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Affiliation(s)
- M Mohan Bhadbhade
- Center for Materials Characterization, National Chemical Laboratory, Pune - 411 008, India
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10
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Vass E, Hollósi M, Besson F, Buchet R. Vibrational spectroscopic detection of beta- and gamma-turns in synthetic and natural peptides and proteins. Chem Rev 2003; 103:1917-54. [PMID: 12744696 DOI: 10.1021/cr000100n] [Citation(s) in RCA: 246] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Elemér Vass
- Department of Organic Chemistry, Eötvös Loránd University, H-1518 Budapest 112, P.O. Box 32, Hungary
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11
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Pohl S, Goddard R, Kubik S. A new cyclic tetrapeptide composed of alternating l -proline and 3-aminobenzoic acid subunits. Tetrahedron Lett 2001. [DOI: 10.1016/s0040-4039(01)01505-2] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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12
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Thakur AK, Kishore R. Influence of hydrophobic interactions on the conformational adaptability of the beta-Ala residue. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2001; 57:455-61. [PMID: 11437949 DOI: 10.1034/j.1399-3011.2001.00839.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The chemical synthesis and X-ray crystal structure analysis of a model peptide incorporating a conformationally flexible beta-Ala residue: Boc-beta-Ala-Pda, 1 (C23H46N2O3: molecular weight = 398.62) have been described. The peptide crystallized in the crystal system triclinic with space group P21: a = 5.116(3) A, b = 5.6770(10) A, c = 21.744(5) A; alpha = 87.45 degrees, beta = 86.87 degrees, gamma = 90.0 degrees; Z = 1. An attractive feature of the crystal molecular structure of 1 is the induction of a reasonably extended backbone conformation of the beta-Ala moiety, i.e. the torsion angles phi approximately -115 degrees, mu approximately 173 degrees and psi approximately 122 degrees, correspond to skew-, trans and skew+ conformation, respectively, by an unbranched hydrophobic alkyl chain, Pda, which prefers an all-anti orientation (theta1 approximately -153 degrees, theta2 approximately ellipsis theta14 approximately +/-178 degrees ). The observation is remarkable because, systematic conformational investigations of short linear beta-Ala peptides of the type Boc-beta-Ala-Xaa-OCH3 (Xaa = Aib or Acc6) have shown that the chemical and stereochemical characters of the neighboring moieties may be critical in dictating the overall folded and/or unfolded conformational features of the beta-Ala residue. The overall conformation of 1 is typical of a 'bar'. It appears convincing that, in addition to a number of hydrophobic contacts between the parallel arranged molecules, an array of conventional N-HellipsisO=C intermolecular H-bonding interactions stabilize the crystal molecular structure. Moreover, the resulting 14-membered pseudo-ring motif, generated by the amide-amide interactions between the adjacent molecules, is completely devoid of nonconventional C-HellipsisO interaction. The potentials of the conformational adaptation of the beta-Ala residue, to influence and stabilize different structural characteristics have been highlighted.
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Affiliation(s)
- A K Thakur
- Institute of Microbial Technology, Chandigarh, India
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13
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Günther R, Hofmann HJ. Hydrazino peptides as foldamers: an extension of the beta-peptide concept. J Am Chem Soc 2001; 123:247-55. [PMID: 11456510 DOI: 10.1021/ja001066x] [Citation(s) in RCA: 77] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Replacing the C(beta) atoms in the beta-amino acid constituents of beta-peptides by nitrogen atoms leads to hydrazino peptides. A systematic conformation analysis of blocked hydrazino peptide oligomers of the general type I at the HF/6-31G, MP2/6-31G, and DFT/B3LYP/6-31G levels of ab initio MO theory and on the basis of molecular mechanics reveals a wide variety of secondary structures, as for instance various helices and sheet- and turnlike conformers. Some of them are closely related to secondary structure types found in beta-peptides; others represent novel types. Thus, a very stable, novel helix with 14-membered hydrogen-bonded pseudocycles, which occupies a conformation space different from that of helices with 14-membered rings found among the most stable conformers in beta-peptides, is indicated. The most important secondary structure elements are characterized by interactions between peptidic NH and CO groups. The additional hydrazino N(alpha)H group takes part in special structuring effects but is of lesser importance for secondary structure formation. The influence of environmental effects on the existence and stability of the various structure types is discussed. Due to the wide variety of structural possibilities, hydrazino peptides might be a useful tool for peptide and protein design.
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Affiliation(s)
- R Günther
- Contribution from the Institute of Biochemistry, Faculty of Biosciences, Pharmacy, and Psychology, University of Leipzig, Talstrasse 33, D-04103 Leipzig, Germany
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14
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DeGrado WF, Schneider JP, Hamuro Y. The twists and turns of beta-peptides. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 1999; 54:206-17. [PMID: 10517158 DOI: 10.1034/j.1399-3011.1999.00131.x] [Citation(s) in RCA: 151] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Recently, it has been discovered that peptides composed of beta-amino acids are capable of adopting novel secondary structures demonstrating that peptides composed of alpha-amino acids are not unique in their ability to fold into well-defined structures. Cyclic as well as acyclic peptides composed of beta-amino acid residues adopt turn, helical, and sheet-like conformations. Here, we discuss the synthesis and conformational preferences of individual, substituted beta-amino acids as well as the structures that peptides composed of these residues, beta-peptides, may adopt.
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Affiliation(s)
- W F DeGrado
- Department of Biochemistry and Biophysics, Johnson Research Foundation, School of Medicine, The University of Pennsylvania, Philadelphia 19104-6059, USA
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15
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Abstract
The conformation of oligomers of beta-amino acids of the general type Ac-[beta-Xaa]n-NHMe (beta-Xaa = beta-Ala, beta-Aib, and beta-Abu; n = 1-4) was systematically examined at different levels of ab initio molecular orbital theory (HF/6-31G*, HF/3-21G). The solvent influence was considered employing two quantum-mechanical self-consistent reaction field models. The results show a wide variety of possibilities for the formation of characteristic elements of secondary structure in beta-peptides. Most of them can be derived from the monomer units of blocked beta-peptides with n = 1. The stability and geometries of the beta-peptide structures are considerably influenced by the side-chain positions, by the configurations at the C alpha- and C beta-atoms of the beta-amino acid constituents, and especially by environmental effects. Structure peculiarities of beta-peptides, in particular those of various helix alternatives, are discussed in relation to typical elements of secondary structure in alpha-peptides.
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Affiliation(s)
- K Möhle
- Institute of Physical and Theoretical Chemistry, Faculty of Chemistry and Mineralogy, Leipzig, Germany
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16
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Lombardi A, Saviano M, Nastri F, Maglio O, Mazzeo M, Isernia C, Paolillo L, Pavone V. Solvent-mediated conformational transition in β-alanine containing cyclic peptides. VIII. Biopolymers 1998. [DOI: 10.1002/(sici)1097-0282(199602)38:6<693::aid-bip2>3.0.co;2-q] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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17
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Lombardi A, Saviano M, Nastri F, Maglio O, Mazzeo M, Isernia C, Paolillo L, Pavone V. Solvent-mediated conformational transition in beta-alanine containing cyclic peptides. VIII. Biopolymers 1996; 38:693-703. [PMID: 8652791 DOI: 10.1002/(sici)1097-0282(199602)38:6%3c693::aid-bip2%3e3.0.co;2-q] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In the present paper we describe the solution nmr structural analysis and restrained molecular dynamic simulation of the cyclic pentapeptide cyclo-(Pro-Phe-Phe-beta-Ala-beta-Ala). The conformational analysis carried out in CD3CN and dimethylsulfoxide (DMSO) solutions by nmr spectroscopy was based on interproton distances derived from rotating frame nuclear Overhauser effect spectroscopy spectra and homonuclear coupling constants. A restrained molecular dynamic simulation in vacuo was also performed to build refined molecular models. The molecule is present in both solvent systems as two slowly interconverting conformers, characterized by a cis-trans isomerism around the beta-Ala5-Pro1 peptide bond. In CD3CN solution, the conformer with a ci5 peptide bond is quite similar to that observed in the solid state, while the conformer containing all trans peptide bonds is characterized by an intramolecular hydrogen bond stabilizing a C10- and a C13-ring structure. In DMSO solution, the trans isomer is partly similar to that observed in CD3CN solution while the cis isomer is different from that observed in the solid state. The effect of the solvent in stabilizing different conformations was also investigated in DMSO-CD3CN solvent mixtures.
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Affiliation(s)
- A Lombardi
- Centro Interdipartimentale di Ricerca su Peptidi Bioattivi, Università di Napoli Federico II, Italy
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18
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Lombardi A, Saviano M, Nastri F, Maglio O, Mazzeo M, Pedone C, Isernia C, Pavone V. Unusual conformational preferences of beta-alanine containing cyclic peptides. VII. Biopolymers 1996; 38:683-91. [PMID: 8652790 DOI: 10.1002/bip.360380602] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
In the present paper we describe the synthesis, purification, and single crystal x-ray analysis of the cyclic pentapeptide cyclo-(Pro-Phe-Phe-beta-Ala-beta-Ala). This compound crystallizes in the orthorhombic space group P2I2I2I from methanol and adopts in the solid state an unusual conformation characterized by a cis beta-Ala5-Pro1 peptide bond and by an intramolecular hydrogen bond stabilizing a C11-and a C12-ring structure. The C11 structure contains the Phe3 and the beta-Ala4 at the corner position of the turn; it is the first observation of a type II beta-turn enlargement due to the insertion of an extra methylene group of the beta-alanine residue. The rest of the molecule participates in a newly characterized C12-ring structure, which incorporates a beta-Ala residue at position i of the turn.
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Affiliation(s)
- A Lombardi
- Centro Interdipartimentale di Ricerca su Peptidi Bioattivi, University of Naples Federico II, Italy
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19
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Pavone V, Lombardi A, Nastri F, Saviano M, Maglio O, D'Auria G, Quartara L, Maggi CA, Pedone C. Design and structure of a novel Neurokinin A receptor antagonist cyclo(-Met1-Asp2-Trp3-Phe4-Dap5-Leu6-)cyclo(2β-5β). ACTA ACUST UNITED AC 1995. [DOI: 10.1039/p29950000987] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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20
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Pavone V, Lombardi A, Saviano M, Di Blasio B, Nastri F, Fattorusso R, Maglio O, Isernia C. Beta-alanine containing cyclic peptides with predetermined turned structure. V. Biopolymers 1994; 34:1505-15. [PMID: 7827262 DOI: 10.1002/bip.360341108] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In the present paper we describe the synthesis, purification, single crystal x-ray analysis, and solution structural characterization by nmr spectroscopy, combined with restrained molecular dynamic simulations, of the cyclic hexapeptide cyclo-(Pro-Phe-beta-Ala-Phe-Phe-beta-Ala). The peptide was synthesized by classical solution methods and the cyclization of the free hexapeptide was accomplished in good yields in diluted methylenechloride solution using N,N-dicyclohexyl-carbodiimide. The compound crystallizes in the monoclinic space group P2(1) from methanol/ethyl acetate. The molecule adopts in the solid state a conformation characterized by cis beta-Ala6-Pro1 peptide bond. The alpha-amino acid residues are at the corner positions of turned structures. The Pro1-Phe2 segment is incorporated in a pseudo type I beta-turn, while Phe4-Phe5 is in a typical type I beta-turn. Assignment of all 1H and 13C resonances was achieved by homo- and heteronuclear two-dimensional techniques in dimethylsulfoxide (DMSO) solutions. The conformational analysis was based on interproton distances derived from rotating frame nuclear Overhauser effect spectroscopy spectra and homonuclear coupling constants. Restrained molecular dynamic simulation in vacuo was also performed to built refined molecular models. The molecule is present in DMSO solution as two slowly interconverting conformers, characterized by a cis-trans isomerism around the beta-Ala6-Pro1 peptide bond. This work confirms our expectations on the low propensity of beta-alanyl residues to be positioned at the corners of turned structure.
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Affiliation(s)
- V Pavone
- Centro Interdipartimentale di Ricerca su Peptidi Bioattivi and CEINGE-Biotecnologie Avanzate, University of Naples, Federico II, Italy
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21
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Pavone V, Lombardi A, Saviano M, Nastri F, Fattorusso R, Maglio O, Isernia C, Paolillo L, Pedone C. Beta-alanine containing cyclic peptides with turned structure: the "pseudo type II beta-turn." VI. Biopolymers 1994; 34:1517-26. [PMID: 7827263 DOI: 10.1002/bip.360341109] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
In the present paper we describe the synthesis, purification, single crystal x-ray analysis, and nmr solution characterization, combined with restrained molecular dynamic simulations, of the cyclic hexapeptide cyclo-(L-Pro-L-Phe-beta-Ala)2. The peptide was synthesized by classical solution methods and the cyclization of the free hexapeptide was accomplished in good yields in diluted methylene chloride solution using N,N-dicyclohexyl-carbodiimide. The compound crystallizes in the monoclinic space group P2(1) from methanol-dichloromethane solution. The two identical halves of the molecule adopt in the solid state two different conformations. One beta-Ala-L-Pro peptide bond is trans, while the second is cis. The molecule is present in dimethylsulfoxide d6 solutions as a mixture of conformational families. One of these corresponds to a C2 symmetrical molecule with both beta-Ala-Pro cis peptide bonds, while the second major conformation is very similar to that observed in the solid state. All Pro-Phe segments, both in the solid state and the symmetrical and unsymmetrical solution conformations, display phi, psi angles close to that of position i + 1 and i + 2 of type II beta-turns. In addition, the segments preceded by a trans beta-Ala-Pro peptide bond are characterized by a typical i<--i + 3 hydrogen bond, which is absent in the conformer containing a cis beta-Ala-Pro peptide bond. The latter conformation corresponds to a new structural domain we define as the "pseudo type II beta-turn."
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Affiliation(s)
- V Pavone
- Centro Interdipartimentale di Ricerca su Peptidi Bioattivi, CEINGE, Biotechnologie Avanzate, University of Naples, Federico II, Italy
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22
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Benedetti E. X-ray crystallography of peptides: the contributions of the Italian laboratories. Biopolymers 1996; 40:3-44. [PMID: 8541447 DOI: 10.1002/(sici)1097-0282(1996)40:1<3::aid-bip2>3.0.co;2-#] [Citation(s) in RCA: 131] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
The review article summarizes the most relevant solid state structural and conformational results obtained in the laboratories involved in Italy in the studies of synthetic and natural peptides by x-ray diffraction analyses. Some of the topics will include research studies carried out in other European countries, whereas in other cases studies carried out in Italy will be included in other review articles included in this volume. The review deals with peptides containing symmetrically achiral and unsymmetrically chiral C alpha,alpha-dialkylated glycine residues, peptides containing beta-alanine residues, alpha,beta-dehydroamino acid residues, and aminosuccinyl residues, peptides containing the thioamide surrogate, heterochiral peptides and several bioactive peptides systems with the proposed relationships between function and structure.
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Affiliation(s)
- E Benedetti
- Biocrystallography Centre, CNR, University of Napoli Federico II, Italy
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