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Crisma M, Toniolo C. Helical screw-sense preferences of peptides based on chiral, Cα-tetrasubstituted α-amino acids. Biopolymers 2016; 104:46-64. [PMID: 25363510 DOI: 10.1002/bip.22581] [Citation(s) in RCA: 68] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2014] [Revised: 10/14/2014] [Accepted: 10/24/2014] [Indexed: 01/09/2023]
Abstract
The preferred helical screw senses of chiral α-amino acids with a C(α)-tetrasubstituted α-carbon atom, as determined in the crystal state by X-ray diffraction analyses on derivatives and peptides, are reviewed. This survey covers C(α)-methylated and C(α)-ethylated α-amino acids, as well as α-amino acids cyclized on the α-carbon, including those characterized by the combination of lack of chirality at the α-carbon with either side-chain or axial chirality. Although, in general, chiral C(α)-tetrasubstituted α-amino acids show a less pronounced bias toward a single helical screw sense than their proteinogenic (C(α)-trisubstituted) counterparts, our analysis highlights significant differences in terms of magnitude and direction of such a bias among the various sub-families of residues, and between individual amino acids within each sub-family as well. The experimental findings can be rationalized, at least in part, on the basis of steric considerations.
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Affiliation(s)
- Marco Crisma
- Institute of Biomolecular Chemistry, Padova Unit, CNR, 35131, Padova, Italy
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2
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Annese C, D'Accolti L, De Zotti M, Fusco C, Toniolo C, Williard PG, Curci R. Concerning selectivity in the oxidation of peptides by dioxiranes. Further insight into the effect of carbamate protecting groups. J Org Chem 2010; 75:4812-6. [PMID: 20560586 DOI: 10.1021/jo100855h] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
With use of methyl(trifluoromethyl)dioxirane (TFDO), the oxidation of some tripeptide esters protected at the N-terminus with carbamate or amide groups could be achieved efficiently under mild conditions with no loss of configuration at the chiral centers. Expanding on preliminary investigations, it is found that, while peptides protected with amide groups (PG = Ac-, Tfa-, Piv-) undergo exclusive hydroxylation at the side chain, their analogues bearing a carbamate group (PG = Cbz-, Moc-, Boc-, TcBoc-) give competitive and/or concurrent hydroxylation at the terminal N-H moiety. Valuable nitro derivatives are also formed as a result of oxidative deprotection of the carbamate group with excess dioxirane. A rationale is proposed to explain the dependence of the selectivity upon the nature of the protecting group.
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Affiliation(s)
- Cosimo Annese
- Dipartimento Chimica, CNR-ICCOM, Università di Bari, v. Amendola 173, 70126 Bari, Italy
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3
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Crisma M, Valle G, Pantano M, Formaggio F, Bonora GM, Toniolo C, Kamphuis J. Peptides from chiral Cαα-disubstituted glycines. On the helical screw sense of isovaline peptides. ACTA ACUST UNITED AC 2010. [DOI: 10.1002/recl.19951140706] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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4
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Licini G, Bonchio M, Broxterman QB, Kaptein B, Moretto A, Toniolo C, Scrimin P. C(alpha)-tetrasubstituted amino acid based peptides in asymmetric catalysis. Biopolymers 2006; 84:97-104. [PMID: 16123989 DOI: 10.1002/bip.20356] [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: 11/07/2022]
Abstract
C(alpha)-tetrasubstituted alpha-amino acids constitute a powerful tool for controlling the conformation of short peptide sequences. Chiral peptides may be used in stereoselective reactions both for asymmetric induction and in kinetic resolution. By reviewing recent data from our own laboratories and by presenting new results on the stereoselective oxidation of chalcone to the corresponding oxide, this contribution shows that the control of peptide conformation is a critical issue in order to achieve successful stereoselective catalysis.
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Affiliation(s)
- Giulia Licini
- Department of Chemical Sciences, University of Padova, 35131 Padova, Italy
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5
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Rainaldi M, Lancelot N, Elbayed K, Raya J, Piotto M, Briand JP, Kaptein B, Broxterman QB, Berkessel A, Formaggio F, Toniolo C, Bianco A. Conformational analysis by HRMAS NMR spectroscopy of resin-bound homo-peptides from C(alpha)-methyl-leucine. Org Biomol Chem 2003; 1:1835-7. [PMID: 12945760 DOI: 10.1039/b303193d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A series of [L-(alphaMe)Leu]n (n = 1-5) homo-peptides have been covalently linked to Tentagel and POEPOP resins and submitted to a conformational study using HRMAS NMR spectroscopy. Whereas the mono- and dipeptide are mainly fully-extended, stable 3(10)-helical structures are formed beginning from the trimer.
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Affiliation(s)
- Mario Rainaldi
- Institute of Biomolecular Chemistry, CNR, Department of Organic Chemistry, University of Padova, 35131 Padova, Italy
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6
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Toniolo C, Crisma M, Formaggio F, Peggion C. Control of peptide conformation by the Thorpe-Ingold effect (C alpha-tetrasubstitution). Biopolymers 2002; 60:396-419. [PMID: 12209474 DOI: 10.1002/1097-0282(2001)60:6<396::aid-bip10184>3.0.co;2-7] [Citation(s) in RCA: 580] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
The preferred conformations of peptides heavily based on the currently extensively exploited achiral and chiral alpha-amino acids with a quaternary alpha-carbon atom, as determined by conformational energy computations, crystal-state (x-ray diffraction) analyses, and solution ((1)H-NMR and spectroscopic) investigations, are reviewed. It is concluded that 3(10)/alpha-helical structures and the fully extended (C(5)) conformation are preferentially adopted by peptide sequences characterized by this family of amino acids, depending upon overall bulkiness and nature (e.g., whether acyclic or C(alpha) (i) <--> C(alpha) (i) cyclized) of their side chains. The intriguing relationship between alpha-carbon chirality and bend/helix handedness is also illustrated. gamma-Bends and semiextended conformations are rarely observed. Formation of beta-sheet structures is prevented.
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Affiliation(s)
- C Toniolo
- Department of Organic Chemistry, University of Padova, Institute of Biomolecular Chemistry, CNR, 35131 Padova, Italy.
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Peggion C, Flammengo R, Mossel E, Broxterman QB, Kaptein B, Kamphuis J, Formaggio F, Crisma M, Toniolo C. Mag: a Cα-Methylated, Side-chain Unsaturated α-Amino Acid. Introduction into Model Peptides and Conformational Preference. Tetrahedron 2000. [DOI: 10.1016/s0040-4020(00)00274-x] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/16/2022]
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9
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Affiliation(s)
- Marco Crisma
- Contribution from the Biopolymer Research Centre, CNR, Department of Organic Chemistry, University of Padova, 35131 Padova, Italy, and Department of Chemistry, Faculty of Science and Technology, Kinki University, Osaka 577, 8502 Japan
| | - Fernando Formaggio
- Contribution from the Biopolymer Research Centre, CNR, Department of Organic Chemistry, University of Padova, 35131 Padova, Italy, and Department of Chemistry, Faculty of Science and Technology, Kinki University, Osaka 577, 8502 Japan
| | - Claudio Toniolo
- Contribution from the Biopolymer Research Centre, CNR, Department of Organic Chemistry, University of Padova, 35131 Padova, Italy, and Department of Chemistry, Faculty of Science and Technology, Kinki University, Osaka 577, 8502 Japan
| | - Taichi Yoshikawa
- Contribution from the Biopolymer Research Centre, CNR, Department of Organic Chemistry, University of Padova, 35131 Padova, Italy, and Department of Chemistry, Faculty of Science and Technology, Kinki University, Osaka 577, 8502 Japan
| | - Tateaki Wakamiya
- Contribution from the Biopolymer Research Centre, CNR, Department of Organic Chemistry, University of Padova, 35131 Padova, Italy, and Department of Chemistry, Faculty of Science and Technology, Kinki University, Osaka 577, 8502 Japan
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10
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Savrda J, Mazaleyrat JP, Wakselman M, Formaggio F, Crisma M, Toniolo C. Synthesis, conformational study, and spectroscopic characterization of the cyclic C alpha, alpha-disubstituted glycine 9-amino-9-fluorenecarboxylic acid. J Pept Sci 1999; 5:61-74. [PMID: 10100122 DOI: 10.1002/(sici)1099-1387(199902)5:2<61::aid-psc173>3.0.co;2-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
A series of terminally blocked peptides (to the pentamer level) from L-Ala and the cyclic C alpha, alpha-disubstituted Gly residue Afc and one Gly/Afc dipeptide have been synthesized by solution method and fully characterized. The molecular structure of the amino acid derivative Boc-Afc-OMe and the dipeptide Boc-Afc-Gly-OMe were determined in the crystal state by X-ray diffraction. In addition, the preferred conformation of all of the model peptides was assessed in deuterochloroform solution by FT-IR absorption and 1H-NMR. The experimental data favour the conclusion that the Afc residue tends to adopt either the fully-extended (C5) or a folded/helical structure. In particular, the former conformation is highly populated in solution and is also that found in the crystal state in the two compounds investigated. A comparison with the structural propensities of the strictly related C alpha, alpha-disubstituted Gly residues Ac5c and D phi g is made and the implications for the use of the Afc residue in conformationally constrained analogues of bioactive peptides are briefly examined. A spectroscopic (UV absorption, fluorescence, CD) characterization of this novel aromatic C alpha, alpha-disubstituted Gly residue is also reported.
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Affiliation(s)
- J Savrda
- SIRCOB, Bât, Lavoisier, University of Versailles, France
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11
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Wolf WM, Stasiak M, Leplawy MT, Bianco A, Formaggio F, Crisma M, Toniolo C. Destabilization of the 310-Helix in Peptides Based on Cα-Tetrasubstituted α-Amino Acids by Main-Chain to Side-Chain Hydrogen Bonds. J Am Chem Soc 1998. [DOI: 10.1021/ja982194c] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Wojciech M. Wolf
- Contribution from the Institute of General and Ecological Chemistry and the Institute of Organic Chemistry, Technical University, 90-924 Lodz, Poland, and the Department of Organic Chemistry and Biopolymer Research Center, CNR, University of Padova, 35131 Padova, Italy
| | - Marcin Stasiak
- Contribution from the Institute of General and Ecological Chemistry and the Institute of Organic Chemistry, Technical University, 90-924 Lodz, Poland, and the Department of Organic Chemistry and Biopolymer Research Center, CNR, University of Padova, 35131 Padova, Italy
| | - Miroslav T. Leplawy
- Contribution from the Institute of General and Ecological Chemistry and the Institute of Organic Chemistry, Technical University, 90-924 Lodz, Poland, and the Department of Organic Chemistry and Biopolymer Research Center, CNR, University of Padova, 35131 Padova, Italy
| | - Alberto Bianco
- Contribution from the Institute of General and Ecological Chemistry and the Institute of Organic Chemistry, Technical University, 90-924 Lodz, Poland, and the Department of Organic Chemistry and Biopolymer Research Center, CNR, University of Padova, 35131 Padova, Italy
| | - Fernando Formaggio
- Contribution from the Institute of General and Ecological Chemistry and the Institute of Organic Chemistry, Technical University, 90-924 Lodz, Poland, and the Department of Organic Chemistry and Biopolymer Research Center, CNR, University of Padova, 35131 Padova, Italy
| | - Marco Crisma
- Contribution from the Institute of General and Ecological Chemistry and the Institute of Organic Chemistry, Technical University, 90-924 Lodz, Poland, and the Department of Organic Chemistry and Biopolymer Research Center, CNR, University of Padova, 35131 Padova, Italy
| | - Claudio Toniolo
- Contribution from the Institute of General and Ecological Chemistry and the Institute of Organic Chemistry, Technical University, 90-924 Lodz, Poland, and the Department of Organic Chemistry and Biopolymer Research Center, CNR, University of Padova, 35131 Padova, Italy
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12
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Biondi L, Filira F, Gobbo M, Pavin E, Rocchi R. Conformational investigations on glycosylated threonine-oligopeptides of increasing chain length. J Pept Sci 1998; 4:58-71. [PMID: 9523756 DOI: 10.1002/(sici)1099-1387(199802)4:1<58::aid-psc129>3.0.co;2-b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Stepwise solution syntheses are described of the homo-oligomers Z-(Thr)n-NHCH3 (n=1-4, I1-4), Z-¿[Gal(Ac)4beta]Thr¿n-NHCH3(n=1-5, II1-5) and Z-[(Galbeta)Thr]n-NHCH3 (n=1-5, III1-5). Members of the III1-5 series were obtained by de-acetylation of the corresponding oligomers of the II1-5 series. The conformational preferences of the terminally protected homo-peptides of the three series were investigated by FT-IR absorption spectroscopy both in the solid state and in CDCl3 solution, at various concentrations. Proton NMR measurements in CDCl3 and in DMSO-d6 were also carried out and the effect of temperature variation on the chemical shifts of amide protons was determined in DMSO-d6 (range 298-335 K) and in CDCl3 (range 298-320K). CD spectra were recorded in water and in TFE. Solubility problems prevented measurements in CDCl3 solution for Z-(Thr)4-NHCH3 and for the entire III1-5 series. The existence of unordered structures in the carbohydrate-free oligomers and of more or less extended, organized structures in the glycosylated derivatives is indicated by the NMR and IR measurements. The sugar moieties apparently show a structure-inducing effect on the peptide chain.
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Affiliation(s)
- L Biondi
- Biopolymer Research Centre, CNR, Department of Organic Chemistry, University of Padova, Italy
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13
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Burgess K, Li W, Lim D, Moye-Sherman D. Comparisons of the conformational biases imposed by trans-2,3-methanomethionine and alpha-methylmethionine. Biopolymers 1997; 42:439-53. [PMID: 9283293 DOI: 10.1002/(sici)1097-0282(19971005)42:4<439::aid-bip7>3.0.co;2-r] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A comparative study of four peptidomimetics of the sequence Phe-Met-Arg-Phe-amide (FMRFa) was performed to compare the conformational bias caused by trans-2,3-methanomethionine and alpha-methylmethionine stereoisomers. The specific compounds studied were {(2S,3S)-cyclo-M} RFa, F{(2R,3R)-cyclo-M} RFa, F{(S)-alpha-Mem} RFa, and F{(R)-alpha-MeM} RFa. Molecular simulations based on CHARMm 22 indicate that gamma-turn, inverse gamma-turn, and alpha-helical conformations about the cyclo-M residue are accessible to the two F{cyclo-M} RFa stereoisomers. Similar calculations for F{(S)-alpha-MeM} RFa, and F{(R)-alpha-MeM}RFa indicate that the alpha-methylamino acids tend to favor alpha-helical conformations. The nmr data is presented for the four peptidomimetics. Most informative were the rotating frame nuclear Overhauser effect cross peaks between the NH protons proximal to the methionine surrogates, and the C beta hydrogens. Overall, these nmr data indicate F{(2S,3S)-cyclo-M} RFa and F{(2R,3R)-cyclo-M} RFa preferentially adopt inverse gamma-turn and gamma-turn conformations, respectively, whereas F{(S)-alpha-MeM} RFa and F{(R)-alpha-MeM} RFa tend to form partial left- and right-handed helical structures (although energy differences between the two turn structures, and between the two helical structures are likely to be small). It is suggested that the wider NH-C alpha-CO angle of cyclopropane amino acids and their more severe steric requirements around the C beta carbons force the peptidomimetic N- and C-termini into the same region of conformational space. This favors C7 turns in the cyclopropane amino acid series relative to the less constrained alpha-methyl derivatives.
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Affiliation(s)
- K Burgess
- Department of Chemistry, Texas A&M University, College Station 77843-3255, USA
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14
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Gatos M, Formaggio F, Crisma M, Valle G, Toniolo C, Bonora GM, Saviano M, Iacovino R, Menchise V, Galdiero S, Pedone C, Benedetti E. Conformational characterization of peptides rich in the cycloaliphatic Cα,α-disubstituted glycine 1-amino-cyclononane-1-carboxylic acid. J Pept Sci 1997. [DOI: 10.1002/(sici)1099-1387(199709)3:5<367::aid-psc116>3.0.co;2-v] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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15
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Gatos M, Formaggio F, Crisma M, Valle G, Toniolo C, Bonora GM, Saviano M, Iacovino R, Menchise V, Galdiero S, Pedone C, Benedetti E. Conformational characterization of peptides rich in the cycloaliphatic C alpha,alpha-disubstituted glycine 1-aminocyclononane-1-carboxylic acid. J Pept Sci 1997; 3:367-82. [PMID: 9391912 DOI: 10.1002/(sici)1099-1387(199709)3:5%3c367::aid-psc116%3e3.0.co;2-v] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
A series of N- and C-protected, monodispersed homo-oligopeptides (to the pentamer level) from the cycloaliphatic C alpha,alpha-dialkylated glycine 1-aminocyclononane-1-carboxylic acid (Ac9c) and two Ala/Ac9c tripeptides have been synthesized by solution methods and fully characterized. The conformational preferences of all the model peptides were determined in deuterochloroform solution by FT-IR absorption and 1H-NMR. The molecular structures of the amino acid derivatives mCIAc-Ac9c-OH and Z-Ac9c-OtBu, the dipeptide pBrBz-(Ac9c)2-OtBu, the tetrapeptide Z-(Ac9c)4-OtBu, and the pentapeptide Z-(Ac9c)5-OtBu were determined in the crystal state by X-ray diffraction. Based on this information, the average geometry and the preferred conformation for the cyclononyl moiety of the Ac9c residue have been assessed. The backbone conformational data are strongly in favour of the conclusion that the Ac9c residue is a strong beta-turn and helix former. A comparison with the structural propensity of alpha-aminoisobutyric acid, the prototype of C alpha,alpha-dialkylated glycines, and the other extensively investigated members of the family of 1-aminocycloalkane-1-carboxylic acids (Acnc, with n = 3-8) is made and the implications for the use of the Ac9c residue in conformationally constrained analogues of bioactive peptides are briefly examined.
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Affiliation(s)
- M Gatos
- Biopolymer Research Centre, CNR, University of Padova, Italy
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16
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Moretto V, Formaggio F, Crisma M, Bonora GM, Toniolo C, Benedetti E, Santini A, Saviano M, Di Blasio B, Pedone C. Preferred conformation of peptides rich in Ac8c, a medium-ring alicyclic C (alpha,alpha)-disubstituted glycine. J Pept Sci 1996; 2:14-27. [PMID: 9225242 DOI: 10.1002/psc.43] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
A complete series of terminally blocked, monodispersed homo-oligopeptides (to the pentamer level) from the sterically demanding, medium-ring alicyclic C (alpha,alpha)-disubstituted glycine 1-aminocyclooctane-1-carboxylic acid (Ac8c), and two Ala/Ac8c tripeptides, were synthesized by solution methods and fully characterized. The preferred conformation of all the oligopeptides was determined in deuterochloroform solution by IR absorption and 1H-NMR. The molecular structures of the amino acid derivative Z-Ac8c-OH, the dipeptide pBrBz-(Ac8c)2-OH and the tripeptide pBrBz-(Ac8c)3-OtBu were assessed in the crystal state by X-ray diffraction. Conformational energy computations were performed on the monopeptide Ac-Ac8c-NHMe. Taken together, the results obtained strongly support the view that the Ac8c residue is an effective beta-turn and helix former. A comparison is also made with the conformational preferences of alpha-aminoisobutyric acid, the prototype of C (alpha,alpha)-disubstituted glycines, and of the other members of the family of 1-aminocycloalkane-1-carboxylic acids (Acnc with n = 3, 5-7) investigated so far. The implications for the use of the Ac8c residue in peptide conformational design are considered.
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Affiliation(s)
- V Moretto
- Department of Organic Chemistry, University of Padova, Italy
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17
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Moretto V, Formaggio F, Crisma M, Bonora GM, Toniolo C, Benedetti E, Santini A, Saviano M, Di Blasio B, Pedone C. Preferred conformation of peptides rich in Ac 8
c, a medium-ring alicyclic C α,α
-disubstituted glycine. J Pept Sci 1996. [DOI: 10.1002/psc.43.o] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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18
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Polese A, Formaggio F, Crisma M, Bonora GM, Toniolo C, Broxterman QB, Kamphuis J. Linear oligopeptides. Part 352. Synthesis, characterization and solution conformational analysis of Cα-methyl-homo-phenylalanine [(αMe)Hph] containing peptides. ACTA ACUST UNITED AC 1996. [DOI: 10.1039/p29960000833] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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19
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Formaggio F, Crisma M, Toniolo C, Benedetti E, Di Blasio B, Saviano M, Galdiero S, Kamphuis J, Santini A. Inversion of 3(10)-helix screw sense in a (D-alpha Me)Leu homo-tetrapeptide induced by a guest D-(alpha Me)Val residue. J Pept Sci 1995; 1:396-402. [PMID: 9223019 DOI: 10.1002/psc.310010607] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
The terminally blocked tetrapeptide pBrBz-[D-(alpha Me)Leu]2-D-(alpha Me)Val-D-(alpha Me)Leu-OfBu is folded in the crystal state in a left-handed 3(10)-helical structure stabilized by two consecutive 1<--4 C = O...H-N intramolecular H-bonds, as determined by X-ray diffraction analysis. A CD study strongly supports the view that this conformation is also that largely prevailing in MeOH solution. A comparison with the published conformation of pBrBz-[D-(alpha Me)Leu]4-OfBu indicates that incorporation of a single internal beta-branched (alpha Me)Val guest residue into the host homo-tetrapeptide from the gamma-branched (alpha Me)Leu residue is responsible for a dramatic structural perturbation, i.e. an inversion of the 3(10) screw sense from right to left-handed.
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Affiliation(s)
- F Formaggio
- Department of Organic Chemistry, University of Padova, Italy
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20
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First unequivocal observation of the multiple fully extended conformation (25-helix) in a homopeptide from a Cα-methylated chiral α-amino acid. ACTA ACUST UNITED AC 1995. [DOI: 10.1007/bf00117951] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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21
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Formaggio F, Pantano M, Crisma M, Bonora GM, Toniolo C, Kamphuis J. Linear oligopeptides. Part 329. Synthesis, characterization and solution conformational analysis of Cα-ethyl, Cα-benzylglycine[(αEt)Phe] containing peptides. ACTA ACUST UNITED AC 1995. [DOI: 10.1039/p29950001097] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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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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