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310 Helix

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Claudio Toniolo – 1st expert on this subject based on the ideXlab platform

  • Looking for the peptide 2.05‐Helix: A solvent‐ and main‐chain length‐dependent conformational switch probed by electron transfer across cα,α‐diethylglycine homo‐oligomers
    Biopolymers, 2013
    Co-Authors: Raffaella Lettieri, Claudio Toniolo, Fernando Formaggio, Marco Crisma, Martina Bischetti, Emanuela Gatto, Antonio Palleschi, Elisabetta Ricci, Mariano Venanzi

    Abstract:

    The elusive, multiple fully extended (2.05-Helix) peptide conformation was searched with a series of Cα,α-diethylglycine homo-oligomers (n = 1 to 5) functionalized by an electron transfer (ET) donor···acceptor (D···A) pair in acetonitrile and chloroform solutions. In the former solvent, all peptides investigated were shown to populate the 310Helix conformation, whereas in chloroform the two shortest members of the series (n = 1 and n = 2) adopt predominantly the 2.05-Helix. Interestingly, for the longest components (n = 3 to n = 5) in this latter solvent, an equilibrium between the 2.05- and 310-helices takes place, the latter conformation becoming progressively more populated as the peptide main-chain length increases. Time-resolved fluorescence (TRF) experiments and molecular mechanics (MM) calculations were used in a combined approach to analyze the ET efficiencies and to associate a specific conformer (from MM) to an experimentally determined ET rate constant (from TRF). Therefore, because of the high sensitivity of the ET process to the D···A distance, ET can be used as a kinetic spectroscopic ruler, allowing for the characterization of the transition from a pure 310Helix conformation to a 2.05-/310Helix equilibrium for the longest Deg homo-peptides of this series upon changing the solvent from acetonitrile to chloroform. To our knowledge, this is the first time that the electronic coupling factor β for ET across a peptide chain in the 2.05-Helix conformation is provided. © 2012 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 51–63, 2013.

  • first homo peptides undergoing a reversible 310 Helix α Helix transition critical main chain length
    Biopolymers, 2008
    Co-Authors: Alessandro Moretto, Fernando Formaggio, Quirinus B Broxterman, Bernard Kaptein, Timothy A Keiderling, Ling Wu, Claudio Toniolo

    Abstract:

    The difference in length between the more elongated peptide 310Helix and the more compact α-Helix is about 0.4 A/residue. This property makes the 310-/α-Helix reversible conversion very promising as a molecular switching tool between the N- and C-terminal functions of a peptide backbone. In this work, using homo-peptides of various main-chain length, all based on the strongly helicogenic, Cα-tetrasubstituted α-amino acid Cα-methyl-L-valine, we show that a well defined, solvent controlled, reversible 310-/α-Helix transition takes place even in a homo-oligomer as short as a terminally blocked hexapeptide. Homo-peptide sequences blocked as a urethane or an acetamide at the N-terminus and as a methyl ester or an N-alkyl amide at the C-terminus are all appropriate. The nature of the occurring helical species in the various solvents tested was assessed by electronic or vibrational circular dichroism. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 567–574, 2008.

    This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

  • First homo‐peptides undergoing a reversible 310Helix/α‐Helix transition: Critical main‐chain length
    Biopolymers, 2008
    Co-Authors: Alessandro Moretto, Fernando Formaggio, Quirinus B Broxterman, Bernard Kaptein, Timothy A Keiderling, Ling Wu, Claudio Toniolo

    Abstract:

    The difference in length between the more elongated peptide 310Helix and the more compact α-Helix is about 0.4 A/residue. This property makes the 310-/α-Helix reversible conversion very promising as a molecular switching tool between the N- and C-terminal functions of a peptide backbone. In this work, using homo-peptides of various main-chain length, all based on the strongly helicogenic, Cα-tetrasubstituted α-amino acid Cα-methyl-L-valine, we show that a well defined, solvent controlled, reversible 310-/α-Helix transition takes place even in a homo-oligomer as short as a terminally blocked hexapeptide. Homo-peptide sequences blocked as a urethane or an acetamide at the N-terminus and as a methyl ester or an N-alkyl amide at the C-terminus are all appropriate. The nature of the occurring helical species in the various solvents tested was assessed by electronic or vibrational circular dichroism. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 567–574, 2008.

    This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

Fernando Formaggio – 2nd expert on this subject based on the ideXlab platform

  • Looking for the peptide 2.05‐Helix: A solvent‐ and main‐chain length‐dependent conformational switch probed by electron transfer across cα,α‐diethylglycine homo‐oligomers
    Biopolymers, 2013
    Co-Authors: Raffaella Lettieri, Claudio Toniolo, Fernando Formaggio, Marco Crisma, Martina Bischetti, Emanuela Gatto, Antonio Palleschi, Elisabetta Ricci, Mariano Venanzi

    Abstract:

    The elusive, multiple fully extended (2.05-Helix) peptide conformation was searched with a series of Cα,α-diethylglycine homo-oligomers (n = 1 to 5) functionalized by an electron transfer (ET) donor···acceptor (D···A) pair in acetonitrile and chloroform solutions. In the former solvent, all peptides investigated were shown to populate the 310Helix conformation, whereas in chloroform the two shortest members of the series (n = 1 and n = 2) adopt predominantly the 2.05-Helix. Interestingly, for the longest components (n = 3 to n = 5) in this latter solvent, an equilibrium between the 2.05- and 310-helices takes place, the latter conformation becoming progressively more populated as the peptide main-chain length increases. Time-resolved fluorescence (TRF) experiments and molecular mechanics (MM) calculations were used in a combined approach to analyze the ET efficiencies and to associate a specific conformer (from MM) to an experimentally determined ET rate constant (from TRF). Therefore, because of the high sensitivity of the ET process to the D···A distance, ET can be used as a kinetic spectroscopic ruler, allowing for the characterization of the transition from a pure 310Helix conformation to a 2.05-/310Helix equilibrium for the longest Deg homo-peptides of this series upon changing the solvent from acetonitrile to chloroform. To our knowledge, this is the first time that the electronic coupling factor β for ET across a peptide chain in the 2.05-Helix conformation is provided. © 2012 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 51–63, 2013.

  • First homo‐peptides undergoing a reversible 310Helix/α‐Helix transition: Critical main‐chain length
    Biopolymers, 2008
    Co-Authors: Alessandro Moretto, Fernando Formaggio, Quirinus B Broxterman, Bernard Kaptein, Timothy A Keiderling, Ling Wu, Claudio Toniolo

    Abstract:

    The difference in length between the more elongated peptide 310Helix and the more compact α-Helix is about 0.4 A/residue. This property makes the 310-/α-Helix reversible conversion very promising as a molecular switching tool between the N- and C-terminal functions of a peptide backbone. In this work, using homo-peptides of various main-chain length, all based on the strongly helicogenic, Cα-tetrasubstituted α-amino acid Cα-methyl-L-valine, we show that a well defined, solvent controlled, reversible 310-/α-Helix transition takes place even in a homo-oligomer as short as a terminally blocked hexapeptide. Homo-peptide sequences blocked as a urethane or an acetamide at the N-terminus and as a methyl ester or an N-alkyl amide at the C-terminus are all appropriate. The nature of the occurring helical species in the various solvents tested was assessed by electronic or vibrational circular dichroism. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 567–574, 2008.

    This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

  • first homo peptides undergoing a reversible 310 Helix α Helix transition critical main chain length
    Biopolymers, 2008
    Co-Authors: Alessandro Moretto, Fernando Formaggio, Quirinus B Broxterman, Bernard Kaptein, Timothy A Keiderling, Ling Wu, Claudio Toniolo

    Abstract:

    The difference in length between the more elongated peptide 310Helix and the more compact α-Helix is about 0.4 A/residue. This property makes the 310-/α-Helix reversible conversion very promising as a molecular switching tool between the N- and C-terminal functions of a peptide backbone. In this work, using homo-peptides of various main-chain length, all based on the strongly helicogenic, Cα-tetrasubstituted α-amino acid Cα-methyl-L-valine, we show that a well defined, solvent controlled, reversible 310-/α-Helix transition takes place even in a homo-oligomer as short as a terminally blocked hexapeptide. Homo-peptide sequences blocked as a urethane or an acetamide at the N-terminus and as a methyl ester or an N-alkyl amide at the C-terminus are all appropriate. The nature of the occurring helical species in the various solvents tested was assessed by electronic or vibrational circular dichroism. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 90: 567–574, 2008.

    This article was originally published online as an accepted preprint. The “Published Online” date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com

Marco Crisma – 3rd expert on this subject based on the ideXlab platform

  • Looking for the peptide 2.05‐Helix: A solvent‐ and main‐chain length‐dependent conformational switch probed by electron transfer across cα,α‐diethylglycine homo‐oligomers
    Biopolymers, 2013
    Co-Authors: Raffaella Lettieri, Claudio Toniolo, Fernando Formaggio, Marco Crisma, Martina Bischetti, Emanuela Gatto, Antonio Palleschi, Elisabetta Ricci, Mariano Venanzi

    Abstract:

    The elusive, multiple fully extended (2.05-Helix) peptide conformation was searched with a series of Cα,α-diethylglycine homo-oligomers (n = 1 to 5) functionalized by an electron transfer (ET) donor···acceptor (D···A) pair in acetonitrile and chloroform solutions. In the former solvent, all peptides investigated were shown to populate the 310Helix conformation, whereas in chloroform the two shortest members of the series (n = 1 and n = 2) adopt predominantly the 2.05-Helix. Interestingly, for the longest components (n = 3 to n = 5) in this latter solvent, an equilibrium between the 2.05- and 310-helices takes place, the latter conformation becoming progressively more populated as the peptide main-chain length increases. Time-resolved fluorescence (TRF) experiments and molecular mechanics (MM) calculations were used in a combined approach to analyze the ET efficiencies and to associate a specific conformer (from MM) to an experimentally determined ET rate constant (from TRF). Therefore, because of the high sensitivity of the ET process to the D···A distance, ET can be used as a kinetic spectroscopic ruler, allowing for the characterization of the transition from a pure 310Helix conformation to a 2.05-/310Helix equilibrium for the longest Deg homo-peptides of this series upon changing the solvent from acetonitrile to chloroform. To our knowledge, this is the first time that the electronic coupling factor β for ET across a peptide chain in the 2.05-Helix conformation is provided. © 2012 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 100: 51–63, 2013.

  • peptide α 310 Helix dimorphism in the crystal state
    Journal of the American Chemical Society, 2007
    Co-Authors: Marco Crisma, Michele Saviano, Alessandro Moretto, Quirinus B Broxterman, Bernard Kaptein, Claudio Toniolo

    Abstract:

    The fully Cα-methylated homo-peptide Ac-[l-(αMe)Val]7-NHiPr is completely 310-helical when its crystals are grown from a methanol solution, whereas it is α-helical when crystallized from HFIP (1,1,1,3,3,3-hexafluoropropan-2-ol), thus providing an example of a solvent-driven α/310Helix dimorphism in the crystal state. The interactions of cocrystallized HFIP molecules with the peptide in the α-helical structure are reported.

  • Peptide α/310Helix Dimorphism in the Crystal State
    Journal of the American Chemical Society, 2007
    Co-Authors: Marco Crisma, Michele Saviano, Alessandro Moretto, Quirinus B Broxterman, Bernard Kaptein, Claudio Toniolo

    Abstract:

    The fully Cα-methylated homo-peptide Ac-[l-(αMe)Val]7-NHiPr is completely 310-helical when its crystals are grown from a methanol solution, whereas it is α-helical when crystallized from HFIP (1,1,1,3,3,3-hexafluoropropan-2-ol), thus providing an example of a solvent-driven α/310Helix dimorphism in the crystal state. The interactions of cocrystallized HFIP molecules with the peptide in the α-helical structure are reported.