551
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Fu Y, Zhou Z, Hazendonk P, Bain AD, Fronczek FR, Escobedo J, McLaughlin ML, Hammer RP. Solution and solid structure of a boc-protected piperidine-spiro-hydantoin as studied by two-dimensional NMR and X-ray crystallography. J Mol Struct 2004. [DOI: 10.1016/j.molstruc.2003.09.013] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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552
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Toniolo C, Formaggio F, Tognon S, Broxterman QB, Kaptein B, Huang R, Setnicka V, Keiderling TA, McColl IH, Hecht L, Barron LD. The complete chirospectroscopic signature of the peptide 310-helix in aqueous solution. Biopolymers 2004; 75:32-45. [PMID: 15307196 DOI: 10.1002/bip.20109] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
We synthesized by solution methods a water-soluble, terminally blocked heptapeptide based on five markedly helicogenic, C(alpha)-tetrasubstituted alpha-amino acids C(alpha)-methyl-L-norvalines and two strongly hydrophilic 2-amino-3-[1-(1,4,7-triazacyclononane)]-L-propanoic acid residues at positions 2 and 5. A Fourier transform infrared absorption and NMR analysis in deuterated chloroform and aqueous solutions of the heptapeptide and two side-chain protected synthetic precursors confirmed our working hypothesis that all oligomers are folded in the 3(10)-helical conformation. Based on these findings, we exploited this heptapeptide as a chiral reference compound for detailed electronic CD, vibrational CD, and Raman optical activity characterizations of the 3(10)-helix in aqueous solution.
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Affiliation(s)
- Claudio Toniolo
- Department of Chemistry, University of Padova, 35131 Padova, Italy.
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553
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Toniolo C, Crisma M, Formaggio F, Peggion C, Broxterman QB, Kaptein B. Molecular spacers for physicochemical investigations based on novel helical and extended peptide structures. Biopolymers 2004; 76:162-76. [PMID: 15054896 DOI: 10.1002/bip.10575] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
A proper understanding of the detailed nature and mechanism of physicochemical interactions depends heavily upon our ability to design and synthesize conformationally constrained 3D structures whose intercomponent geometry (either rigorously rigid or able to undergo destructuration, if required, but in all cases precisely tunable) would be well defined. To this end we have recently reported a few initial studies and we are currently working on the exploitation of stable, short, helical peptide spacers based on achiral and/or chiral Calpha-tetrasubstituted alpha-amino acids. These building blocks are known to force the peptides either to predominantly fold into a 3(10)-helical structure or to adopt a fully extended, planar 2.0(5)-helix. The systems under investigation involve a donor and an acceptor moiety linked to the N- and C-termini of the oligopeptide spacer main chain. By increasing the number of intervening residues the donor.acceptor separation can be easily modulated. This review highlights details of these two novel peptide secondary structures and their use as molecular spacers in physicochemical investigations.
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Affiliation(s)
- Claudio Toniolo
- Institute of Biomolecular Chemistry, CNR, Department of Organic Chemistry, University of Padova, 35131 Padova, Italy.
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554
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Cativiela C, Díaz-De-Villegas MD, Gálvez JA, Ronco E. Allylation and propargylation of chiral cyanopropanoates: An efficient route to long chain α-substituted α-methyl α-amino acids. Chirality 2003; 16:106-11. [PMID: 14712473 DOI: 10.1002/chir.10312] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
alpha-Methyllysine and 2-amino-2-methylundecanoic acid, two alpha,alpha-disubstituted unnatural glycines, were synthesized using highly diastereoselective allylation or propargylation of chiral (1S,2R,4R)-10-dicyclohexylsulfamoylisobornyl 2-cyanopropanoate as the key step to introduce the long side chain. Chirality 16:106-111, 2004.
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Affiliation(s)
- Carlos Cativiela
- Departamento de Química Orgánica, Facultad de Ciencias-Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, E-50009 Zaragoza, Spain
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555
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Wieczorek R, Dannenberg JJ. Hydrogen-Bond Cooperativity, Vibrational Coupling, and Dependence of Helix Stability on Changes in Amino Acid Sequence in Small 310-Helical Peptides. A Density Functional Theory Study. J Am Chem Soc 2003; 125:14065-71. [PMID: 14611243 DOI: 10.1021/ja034034t] [Citation(s) in RCA: 90] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Five pentapeptides, GGGGG, GAGGG, GVGGG, GLGGG, and GIGGG, have been completely optimized in the 3(10)-helical and open beta-strand conformations at the B3LYP/D95 level. The energies of the helices relative to the beta-strands vary from -2.1 to -3.6 kcal and depend on the amino acid residue sequence. The energies of substituting A, V, L, or I for G in the second position are also presented. Vibrational analyses were performed on the optimized structures. Vibrational coupling through the individual H-bond chains of the helices is confirmed to be stronger than that through space or through the covalent bonds. The cooperative interactions of the H-bonds are evident from both the structures and the coupling of the amide I, amide II, and N-H vibrations.
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Affiliation(s)
- Robert Wieczorek
- Department of Chemistry, City University of New York, Hunter College and the Graduate School, 695 Park Avenue, New York, NY 10021, USA
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556
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Datta S, Rathore RNS, Vijayalakshmi S, Vasudev PG, Rao RB, Balaram P, Shamala N. Peptide helices with pendant cycloalkane rings. Characterization of conformations of 1-aminocyclooctane-1-carboxylic acid (Ac8
c) residues in peptides. J Pept Sci 2003; 10:160-72. [PMID: 15113088 DOI: 10.1002/psc.507] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
A pentapeptide, Boc-Leu-Ac8c-Ala-Leu-Ac8c-OMe 1, an octapeptide, Boc-Leu-Ac8c-Ala-Leu-Ac8c-Ala-Leu-Ac8c-OMe 2 and a tripeptide, Boc-Aib-Ac8c-Aib-OMe 3 containing the 1-aminocyclooctane-1-carboxylic acid residue (Ac8c) were synthesized and conformationally characterized by x-ray diffraction studies in the crystal state. Peptides 1 and 2 were also studied by NMR in CDC13 solution. Peptide 1 adopts a purely 3(10)-helical conformation in crystals, stabilized by three intramolecular 1 <-- 4 hydrogen bonds. Peptide 2 in crystals is largely 3(10)-helical with distortion in the backbone at the N-terminus by the insertion of a water molecule between Ac8c (2) CO and Ala (6) NH groups. Peptide 3 forms a C10-ring structure, i.e. a type III (III') beta- turn conformation stabilized by an intramolecular 1 <-- 4 hydrogen bond. Five cyclooctane rings assume boat-chair conformations, whereas the sixth [Ac8c(8) in 2] is appreciably distorted, resembling a chiral intermediate in the pseudorotational pathway from the boat-chair to the twisted boat-chair conformation. Internal bond angles of the cyclooctane rings are appreciably distorted from the tetrahedral value, a characteristic feature of the cyclooctane ring. Peptide 1 crystallized in the space group P212121 with a = 11.900(4) A, b = 18.728(6) A, c = 20.471(3) A and Z = 4. The final R1 and wR2 values are 0.0753 and 0.2107, respectively, for 3901 observed reflections [Fo > or = 3 sigma (Fo)]. Peptide 2 crystallized in space group P21 with a = 12.961(5) A, b = 17.710(10) A, c = 15.101(7) A, beta = 108.45(4) degrees and Z = 2. The final R1 and wR2 values are 0.0906 and 0.1832, respectively, for 2743 observed reflections [Fo > or = 3sigma (Fo)]. 1H-NMR studies on both the peptides strongly suggest the persistence of 3(10)-helical conformations in solution. Peptide 3 crystallized in the space group P21/n, with a = 10.018(1) A, b = 20.725(1) A, c = 12.915(1) A and Z = 4. The final R1 and wR2 values are 0.0411 and 0.1105, respectively, for 3634 observed reflections [Fo > or = 4sigma (Fo)].
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Affiliation(s)
- Saumen Datta
- Department of Physics, Indian Institute of Science, Bangalore-560012, India
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557
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Formaggio F, Crisma M, Toniolo C, Broxterman QB, Kaptein B, Corbier C, Saviano M, Palladino P, Benedetti E. Cα-Methyl, Cα-n-Propylglycine Homo-oligomers. Macromolecules 2003. [DOI: 10.1021/ma030327v] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
| | | | | | | | | | - Catherine Corbier
- Laboratory of Crystallography, ESA 7036, Université Henry Poincaré−Nancy I, 54506 Vandoeuvre-lès-Nancy, France
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558
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Imbriglio JE, Vasbinder MM, Miller SJ. Dual Catalyst Control in the Amino Acid-Peptide-Catalyzed Enantioselective Baylis−Hillman Reaction. Org Lett 2003; 5:3741-3. [PMID: 14507219 DOI: 10.1021/ol035466b] [Citation(s) in RCA: 153] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
[reaction: see text] Nucleophile-loaded peptides and proline have been found to function synergistically as cocatalysts for the asymmetric ketone-based Baylis-Hillman reaction. Although neither compound is effective independently in terms of rate or enantioselectivity, their combination leads to catalysis where enantioselectivities up to 81% have been observed.
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Affiliation(s)
- Jason E Imbriglio
- Department of Chemistry, Merkert Chemistry Center, Boston College, Chestnut Hill, Massachusetts 02467, USA
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559
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Casanovas J, Jiménez AI, Cativiela C, Pérez JJ, Alemán C. N-acetyl-N'-methylamide derivative of (2S,3S)-1-amino-2,3-diphenylcyclopropanecarboxylic acid: theoretical analysis of the conformational impact produced by the incorporation of the second phenyl group to the cyclopropane analogue of phenylalanine. J Org Chem 2003; 68:7088-91. [PMID: 12946154 DOI: 10.1021/jo034720a] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The intrinsic conformational preferences of (2S,3S)-1-amino-2,3-diphenylcyclopropanecarboxylic acid, a phenylalanine cyclopropane analogue bearing two phenyl substituents, have been examined theoretically. For this purpose, its N-acetyl-N'-methylamide derivative, Ac-(2S,3S)c(3)diPhe-NHMe, has been investigated by using ab initio HF and DFT methods. Results have been compared with those previously reported for other cyclopropane analogues of phenylalanine, and with experimental data available for c(3)diPhe-containing peptides.
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Affiliation(s)
- Jordi Casanovas
- Departament de Química, Escola Universitària Politècnica, Universitat de Lleida, c/Jaume II No. 69, 25001 Lleida, Spain.
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560
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Sartori E, Toffoletti A, Rastrelli F, Corvaja C, Bettio A, Formaggio F, Oancea S, Toniolo C. Intramolecular Interaction between Nitroxide Radical and Photoexcited Benzophenone Triplet Linked to Peptide Templates. J Phys Chem A 2003. [DOI: 10.1021/jp0345203] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- E. Sartori
- Department of Physical Chemistry and Institute of Biomolecular Chemistry, CNR and Department of Organic Chemistry, University of Padova, I-35131 Padova, Italy
| | - A. Toffoletti
- Department of Physical Chemistry and Institute of Biomolecular Chemistry, CNR and Department of Organic Chemistry, University of Padova, I-35131 Padova, Italy
| | - F. Rastrelli
- Department of Physical Chemistry and Institute of Biomolecular Chemistry, CNR and Department of Organic Chemistry, University of Padova, I-35131 Padova, Italy
| | - C. Corvaja
- Department of Physical Chemistry and Institute of Biomolecular Chemistry, CNR and Department of Organic Chemistry, University of Padova, I-35131 Padova, Italy
| | - A. Bettio
- Department of Physical Chemistry and Institute of Biomolecular Chemistry, CNR and Department of Organic Chemistry, University of Padova, I-35131 Padova, Italy
| | - F. Formaggio
- Department of Physical Chemistry and Institute of Biomolecular Chemistry, CNR and Department of Organic Chemistry, University of Padova, I-35131 Padova, Italy
| | - S. Oancea
- Department of Physical Chemistry and Institute of Biomolecular Chemistry, CNR and Department of Organic Chemistry, University of Padova, I-35131 Padova, Italy
| | - C. Toniolo
- Department of Physical Chemistry and Institute of Biomolecular Chemistry, CNR and Department of Organic Chemistry, University of Padova, I-35131 Padova, Italy
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561
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D'Amore M, Improta R, Barone V. Conformational Behavior and Magnetic Properties of a Nitroxide Amino Acid Derivative in Vacuo and in Aqueous Solution. J Phys Chem A 2003. [DOI: 10.1021/jp030188j] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Maddalena D'Amore
- Contribution from Dipartimento di Chimica, Universita Federico II, Complesso Universitario Monte S.Angelo, via Cintia, I-80126 Napoli, Italy
| | - Roberto Improta
- Contribution from Dipartimento di Chimica, Universita Federico II, Complesso Universitario Monte S.Angelo, via Cintia, I-80126 Napoli, Italy
| | - Vincenzo Barone
- Contribution from Dipartimento di Chimica, Universita Federico II, Complesso Universitario Monte S.Angelo, via Cintia, I-80126 Napoli, Italy
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562
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Crisma M, Formaggio F, Ruzza P, Calderan A, Elardo S, Borin G, Toniolo C. N-benzhydryl-glycolamide: the first protecting group in peptide synthesis with a strong conformational bias. Biopolymers 2003; 71:17-27. [PMID: 12712498 DOI: 10.1002/bip.10373] [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: 11/09/2022]
Abstract
We have synthesized and examined the preferred conformation of a set of N-benzhydryl-glycolamide esters from N(alpha)-protected (or N(alpha)-blocked) alpha-amino acids. Experiments were performed in CDCl(3) solution by Fourier transform infrared absorption and (1)H-NMR techniques, and in the crystalline state by x-ray diffraction. The results of our analysis strongly support the view that this type of N(alpha)-acylated alpha-aminoacyl esters has a marked tendency to fold into a beta-turn conformation, the nature of which is dictated by the structural propensity of the amino acid constituent at the i+1 position.
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Affiliation(s)
- Marco Crisma
- Institute of Biomolecular Chemistry, Padova Unit, CNR, Department of Organic Chemistry, University of Padova, Italy.
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563
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Formaggio F, Bettio A, Moretto V, Crisma M, Toniolo C, Broxterman QB. Disruption of the beta-sheet structure of a protected pentapeptide, related to the beta-amyloid sequence 17-21, induced by a single, helicogenic C(alpha)-tetrasubstituted alpha-amino acid. J Pept Sci 2003; 9:461-6. [PMID: 12916643 DOI: 10.1002/psc.503] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Fifteen years ago it was shown that an alpha-aminoisobutyric acid (Aib) residue is significantly more effective than an L-Pro or a D-amino acid residue in inducing beta-sheet disruption in short model peptides. As this secondary structure element is known to play a crucial role in the neuropathology of Alzheimer's disease, it was decided to check the effect of Aib (and other selected, helix inducer, C(alpha)-tetrasubstituted alpha-amino acids) on the beta-sheet conformation adopted by a protected pentapeptide related to the sequence 17-21 of the beta-amyloid peptide. By use of FT-IR absorption and 1H NMR techniques it was found that the strong self-association characterizing the pentapeptide molecules in weakly polar organic solvents is completely abolished by replacing a single residue with Aib or one of its congeners.
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Affiliation(s)
- Fernando Formaggio
- Institute of Biomolecular Chemistry, CNR, Department of Organic Chemistry, University of Padova, 35131 Padova, Italy.
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564
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Bertocco A, Formaggio F, Toniolo C, Broxterman QB, Epand RF, Epand RM. Design and function of a conformationally restricted analog of the influenza virus fusion peptide. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2003; 62:19-26. [PMID: 12787447 DOI: 10.1034/j.1399-3011.2003.00063.x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
A conformationally restricted analog of the N-terminal 12-residue peptide segment of the HA2 subunit of the PPV/34, PR/8/34, and Jap/57 strains of influenza virus hemagglutinin was synthesized containing three residues of Calpha-methyl-valine. This peptide has a higher content of helical structure in the presence of 50% trifluoroethanol or when interacting with liposomes of egg phosphatidylcholine compared with the conformationally more flexible control peptide with the native sequence. The control and analog peptides had opposite effects on membrane curvature as measured by shifts in the bilayer-to-hexagonal phase transition temperature of a synthetic phosphatidylethanolamine derivative. The control peptide promoted more negative curvature, particularly at acidic pH and was also more potent than the analog in promoting lipid mixing. The results indicate that the ability of the peptide to sample a broader range of conformations is required for the influenza fusion peptide to destabilize membranes and that a rigid helical structure is less fusogenic. The difference between the two peptides and between pH 7.4 and pH 5.0 show a correlation between the ability to promote negative curvature and to accelerate lipid mixing.
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Affiliation(s)
- A Bertocco
- Institute of Biomolecular Chemistry, CNR, Department of Organic Chemistry, University of Padova, 35131 Padova, Italy
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565
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Aschi M, Lucente G, Mazza F, Mollica A, Morera E, Nalli M, Paglialunga Paradisi M. Peptide backbone folding induced by the C(alpha)-tetrasubstituted cyclic alpha-amino acids 4-amino-1,2-dithiolane-4-carboxylic acid (Adt) and 1-aminocyclopentane-1-carboxylic acid (Ac5c). A joint computational and experimental study. Org Biomol Chem 2003; 1:1980-8. [PMID: 12945783 DOI: 10.1039/b212247b] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The conformational study of a new group of synthetic peptides containing 4-amino-1,2-dithiolane-4-carboxylic acid (Adt), a cysteine-related achiral residue, has been carried out through a joint application of computational and experimental methodologies. Molecular Dynamics simulations clearly suggest the tendency of this molecule to adopt a gamma-turn conformation in vacuum and help in analyzing the complex and crucial conformational behaviour of the dithiolane ring which appears to preferentially adopt a C(S)-like structure. Electronic structure calculations carried out in solution using the Density Functional Theory also indicate the preservation of the gamma-like folding in apolar solvents and the helix-like one in more polar solvents. A comparison with the achiral 1-aminocycloalkane-1-carboxylic acid (Ac5c) has been carried out using the same computational tools. NMR and IR data on dipeptide derivatives containing the Adt or Ac5c residue show that in chloroform solution all the models prefer a gamma-turn structure, centered at the cyclic residue, stabilized by an intramolecular H-bond, whereas in a more polar solvent, i.e. dimethyl sulfoxide, this folding is not maintained. The experimental conformational studies, extended to N-Boc protected tripeptides, clearly indicate the remarkable tendency of both the five-membered C(alpha)-tetrasubstituted cyclic amino acids Adt and Ac5c to induce the gamma-turn structure also in models able to adopt the beta-bend conformation.
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Affiliation(s)
- Massimiliano Aschi
- Dipartimento di Chimica, Ingegneria Chimica e Materiali-Università di L'Aquila, 1-67100 Coppito, L'Aquila, Italy
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566
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Oancea S, Formaggio F, Campestrini S, Broxterman QB, Kaptein B, Toniolo C. Distance dependency of exciton coupled circular dichroism using turn and helical peptide spacers. Biopolymers 2003; 72:105-15. [PMID: 12583013 DOI: 10.1002/bip.10315] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Porphyrins are promising chromophores for the investigation of the still unexplored area of 3-dimensional structural studies of proteins by using the exciton coupled circular dichroism (CD) method. The synthesis, conformational characterization by FTIR absorption and (1)H-NMR, and CD properties are described for a model bis-porphyrin system based on homooligo-[L-(alphaMe)Val](n) peptides as rigid spacers. In particular, the coupled CD phenomenon is experimentally detected, the intensity of which is modulated by the interchromophoric distance. These results extend and integrate those already reported with steroid, dimeric steroid, and brevetoxin bridges.
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Affiliation(s)
- Simona Oancea
- Institute of Biomolecular Chemistry, CNR, Department of Organic Chemistry, University of Padova, 35131 Padova, Italy
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567
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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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568
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Witkowska R, Zabrocki J, Spisani S, Falzarano MS, Toniolo C, Formaggio F. Synthetic formyl tripeptide chemoattractants: a C(alpha,alpha)-dialkylated, amphiphilic glycyl residue at position 1. J Pept Sci 2003; 9:354-60. [PMID: 12846481 DOI: 10.1002/psc.461] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The two diastereomeric tripeptides f-(S)-HmMet-Leu-Phe-OMe and f-(R)-HmMet-Leu-Phe-OMe, analogues of the prototypical chemoattractant f-Met-Leu-Phe-OH, were synthesized in solution by classical methods and fully characterized. A conformational study was performed in solution by 1H-NMR. Concomitantly, the two peptides were tested for their ability to induce chemotaxis, superoxide anion production and lysozyme secretion from human neutrophils. The conformational and biological data are discussed with regard to the proposed model of the chemotactic receptor on neutrophils.
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Affiliation(s)
- Renata Witkowska
- Institute of Organic Chemistry, Technical University of Lodz, 90-924 Lodz, Poland
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569
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Jiménez AI, Marraud M, Cativiela C. Cyclopropane analogue of valine: influence of side chain orientation on peptide folding. Tetrahedron Lett 2003. [DOI: 10.1016/s0040-4039(03)00514-8] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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570
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Antonello S, Formaggio F, Moretto A, Toniolo C, Maran F. Anomalous distance dependence of electron transfer across peptide bridges. J Am Chem Soc 2003; 125:2874-5. [PMID: 12617644 DOI: 10.1021/ja029787e] [Citation(s) in RCA: 97] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The first investigation on the distance dependence of a dissociative electron transfer process across peptide bridges is reported. This study was carried out by using a series of donor-peptide-acceptor systems in which the donor is a phthalimido moiety, the peptide bridges are provided by alpha-aminoisobutyric acid (Aib) homooligomers, and the acceptor is a peroxide functional group. The intramolecular electron transfer from the electrogenerated phthalimido radical anion to the peroxide was studied in comparison with the thermodynamic and kinetic information obtained with models of the acceptor and the donor. The intramolecular rate constants were determined in N,N-dimethylformamide by taking into account the corresponding intermolecular values. The experimental results point to an unusual non-exponential dependence of the intramolecular electron transfer rate on the number of bridge units. The same trend could be verified also by taking into account the actual donor-acceptor edge-to-edge distance. The peculiar distance dependence that was observed for the intramolecular electron transfer rate is attributed to the mediating effect of the intramolecular C=O...H-N hydrogen bonds.
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Affiliation(s)
- Sabrina Antonello
- Dipartimento di Chimica Fisica, Università di Padova, via Loredan 2, 35131 Padova, Italy
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571
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Belokon’ YN, Bhave D, D'Addario D, Groaz E, Maleev V, North M, Pertrosyan A. Catalytic, asymmetric synthesis of α,α-disubstituted amino acids. Tetrahedron Lett 2003. [DOI: 10.1016/s0040-4039(03)00170-9] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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572
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Peggion C, Formaggio F, Crisma M, Toniolo C, Jiménez AI, Cativiela C, Kaptein B, Broxterman QB, Saviano M, Benedetti E. Folding of peptides characterized by c3Val, a highly constrained analogue of valine. Biopolymers 2003; 68:178-91. [PMID: 12548622 DOI: 10.1002/bip.10295] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
Using a combined chemical/chiral chromatographic approach we synthesized an N-protected derivative of (R)-c(3)Val, a severely conformationally restricted C(alpha)-tetrasubstituted alpha-amino acid characterized by a C(beta,beta)-dimethylated cyclopropane system. A set of terminally protected derivatives and model peptides (to the heptamer level), containing one or two (R)-c(3)Val residues in combination with either Aib or Gly residues, was prepared by solution methods. A detailed solution and crystal-state conformational investigation, based on Fourier transform infrared (FTIR) absorption, (1)H-NMR, and x-ray diffraction techniques, performed in comparison with a similar study on related derivatives and peptides rich in (alphaMe)Val, the prototype of C(alpha)-tetrasubstituted alpha-amino acids of this subfamily, allowed us to conclude the following: (a) c(3)Val is a good beta-bend and helix former, although less efficient than (alphaMe)Val. (b) The relationship between alpha-carbon chirality and screw sense of the folded structure formed is the same as that of (alphaMe)Val, i.e., the (R)-enantiomer has a strong left-handed bias. (c) c(3)Val seems more prone than (alphaMe)Val to fold into a gamma-bend conformation. The conformational propensities of C(beta,beta)-disubstituted Ac(3)c residues are also discussed in comparison with those of the parent cyclopropane residue.
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Affiliation(s)
- Cristina Peggion
- Institute of Biomolecular Chemistry, CNR, Department of Organic Chemistry, University of Padova, 35131 Padova, Italy
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573
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Crisma M, Moretto A, Rainaldi M, Formaggio F, Broxterman QB, Kaptein B, Toniolo C. Crystal-state 3D-structural characterization of novel 310-helical peptides. J Pept Sci 2003; 9:620-37. [PMID: 14620128 DOI: 10.1002/psc.482] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
The crystal-state conformations of two octapeptides, pBrBz-(D-Iva)8-OtBu (8I) and Ac-[L-(alphaMe)Val]8-OH (8II), the heptapeptide Z-[L-(alphaMe)Val]7-OH (7), the hexapeptide Z-[L-(alphaMe)Leu]6-OtBu (6) and the tetrapeptide alkylamide Z-(Aib)2-L-Glu(OMe)-L-Ala-L-Lol (5) were assessed by x-ray diffraction analyses. Two independent molecules are observed in the asymmetric unit of each L-(alphaMe)Val homo-peptide. All four homo-peptides are folded in a regular 3(10)-helical structure (only the C-terminal H-bonded conformation of the D-Iva octapeptide is distorted to a type-I beta-turn). The hydroxyl groups of the C-terminal carboxyl moieties of the two L-(alphaMe)Val homo-peptides participate in an oxy-analogue of the type-III beta-turn conformation. While the two L-(alphaMe)Val 3(10)-helices are right-handed, the D-Iva and L-(alphaMe)Leu helices are left-handed. The tetrapeptide alkylamide is 3(10)-helical at the N-terminus, but it is mixed 3(10)/alpha-helical at the C-terminus.
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Affiliation(s)
- Marco Crisma
- Institute of Biomolecular Chemistry, CNR, Department of Organic Chemistry, University of Padova, Padova, Italy.
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574
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Gaucher A, Barbeau O, Hamchaoui W, Vandromme L, Wright K, Wakselman M, Mazaleyrat JP. Synthesis of [18-C-6]-β3-(L)-DOPA, first β-amino acid with a crown-ether receptor side-chain. Tetrahedron Lett 2002. [DOI: 10.1016/s0040-4039(02)02035-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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