Electronic Circular Dichroism of Peptides

Toniolo, Claudio; Formaggio, Fernando; Woody, Robert W.

doi:10.1002/9781118120392.ch15

Cited by 47 publications

(50 citation statements)

References 270 publications

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“…No noticeable changes occurred up to 100 and 48 h, respectively. Moreover, we did not observe any increase of the 222 nm/208 nm ellipticity ratio, indicative of peptide aggregation [32]. Apparently, the absence of conformational transitions over time, reported for aqueous solutions [23], can be ascribed to the presence of the vesicles or of the membrane mimetic solvent TFE.…”

Section: Conformational Analysismentioning

confidence: 43%

Innovative chemical synthesis and conformational hints on the lipopeptide liraglutide

Guryanov

Bondesan²,

Visentini³

et al. 2016

J. Pept. Sci.

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Liraglutide is a new generation lipopeptide drug used for the treatment of type II diabetes. In this work, we describe new approaches for its preparation fully by chemical methods. The key step of these strategies is the synthesis in solution of the Lys/γ-Glu building block, Fmoc-Lys-(Pal-γ-Glu-OtBu)-OH, in which Lys and Glu residues are linked through their side chains and γ-Glu is N(α) -palmitoylated. This dipeptide derivative is then inserted into the peptide sequence on solid phase. As liraglutide is obtained with great purity and high yield, our approach can be particularly attractive for an industrial production. We also report here the results of a circular dichroism conformational analysis in a membrane mimetic environment that offers new insights into the mechanism of action of liraglutide. Copyright © 2016 European Peptide Society and John Wiley & Sons, Ltd.

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Section: Conformational Analysismentioning

confidence: 43%

Innovative chemical synthesis and conformational hints on the lipopeptide liraglutide

Guryanov

Bondesan²,

Visentini³

et al. 2016

J. Pept. Sci.

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“…[4][5][6][7][8][9][10][11] In addition to the g-turn, which represents the main focus of this article and is discussed below, other types of peptide folding motifs have been mentioned and reported in the literature, albeit rarely. 1), despite being less abundant in peptides and proteins than b-turns, 4,8,9,11,[20][21][22][23][24][25][26] are by far more extensively investigated than any other type of turn. 18,19 2.…”

Section: Introductionmentioning

confidence: 99%

Single and multiple peptide γ-turns: literature survey and recent progress

et al. 2015

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In contrast to the extensively investigated b-turn conformation in peptides and proteins, single and multiple g-turns have been much less commonly studied. Single and non-contiguous multiple g-turns have been relatively often authenticated in small cyclic peptides, but these important peptide mainchain reversal motifs have not been examined carefully either in linear peptides or in globular proteins.This Perspective article summarizes literature data on this aspect of peptide stereochemistry, expanding the discussion also to the rarely found, contiguous multiple g-turns which generate incipient or fullydeveloped 2.2 7 -(g-) helices. Unpublished results of recent research activities on this topic ongoing in our laboratories are also briefly outlined.L-amino acids are labeled. In C, a g-turn enclosed into a larger e-turn (C 11 form) is illustrated.

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“…It is clear that this type of CD curve is remarkably different from all those representative of the classical peptide and protein conformations [α‐helix, 3 10 ‐helix, β‐sheet structure, type‐II poly (Pro) n helix] . On these bases, and considering the short main‐chain length of the peptide examined and the number of detailed CD investigations performed on folded sequences adopting β‐ and γ‐turn conformations, we favor the conclusion that the CD spectrum in Figure would result from a combination of those arising from an ‐( S )‐Ala‐( R )‐(αMe)Aze‐ type‐II β‐turn conformer (termed class B spectrum, with its strong negative and strong positive amide π → π* bands near 190 and 205 nm, respectively) accompanied by a strong positive amide n → π* band near 220 nm associated with a γ‐turn conformer centered on ( R )‐(αMe)Aze. According to these assignments, the solvent‐dependent relative height of the 205 and 220 nm bands is attributed to an increase of the type‐II β‐turn (in MeOH) or of the γ‐turn (in either TFE or acetonitrile) population in the solution equilibrium mixture.…”

Section: Resultsmentioning

confidence: 81%

Heterochiral Ala/(αMe)Aze sequential oligopeptides: Synthesis and conformational study

Drouillat

Peggion

Biondi

et al. 2019

Journal of Peptide Science

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α-Amino acid residues with a ϕ,ψ constrained conformation are known to significantly bias the peptide backbone 3D structure. An intriguing member of this class of compounds is (αMe)Aze, characterized by an N α -alkylated four-membered ring and C α -methylation. We have already reported that (S)-(αMe)Aze, when followed by (S)-Ala in the homochiral dipeptide sequential motif -(S)-(αMe)Aze-(S)-Ala-, tends to generate the unprecedented γ-bend ribbon conformation, as formation of a regular, fully intramolecularly H-bonded γ-helix is precluded, due to the occurrence of a tertiary amide bond every two residues. In this work, we have expanded this study to the preparation and 3D structural analysis of the heterochiral (S)-Ala/(R)-(αMe) Aze sequential peptides from dimer to hexamer. Our conformational results show that members of this series may fold in type-II β-turns or in γ-turns depending on the experimental conditions. KEYWORDS azetidines, heterochiral sequences, peptide conformation, peptide synthesis, X-ray diffraction, β/γturns 1 | INTRODUCTION Main-chain reversals (turns) in naturally occurring and synthetic polypeptide molecules are ubiquitous. 1,2 Among them (α-, 3 β-, 4-7 γ-, 8-12 δ-, 13 ε-, 14 and π-15 turns), β-turns are by far the most extensively investigated both experimentally and computationally. All other types of turns, although drastically less frequently reported, are currently the focus of an increasing number of publications, in particular γ-turns. 12Except for the case of αand β-turns (a repetition of one type of αturn generates the classical α-helix 16 while that of some β-turns produces either the 3 10 -helix, 17-20 also well known, particularly in the peptide structural biochemistry literature, or β-turn ribbons 21-23 ), incipient helices or ribbon-like stretches 23,24 arising from all other types of turns have attracted much less interest from chemists.Recently, with the aim at reducing this gap, we focused our attention on γ-turns. 12,24 We wished in particular to discover and investigate in detail noncoded α-amino acids with a high propensity to fold into single turns, and possibly offering a good chance to create new, longer ordered secondary structures. To this end, we especially considered two C α -tetrasubstituted α-amino acids as potentially very promising building blocks, the chiral (αMe)Aze 24-31 (Figure 1) and the achiral 2-aminoadamantane-2-carboxylic acid. 32 In particular, by examining a series of repeating, homochiral, sequential -(S)-(αMe)Aze-(S)-Ala-dipeptides, we found a novel stable peptide conformation, the γ-bend ribbon structure, 24 characterized by only half of the C¼O … H-N intramolecular H-bonds typical of the γ-helix 12 because the strong γ-bend inducer (αMe)Aze, which forms Xxx-(αMe)Aze tertiary amides, lacks the N-H donor function.

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Electronic Circular Dichroism of Peptides

Cited by 47 publications

References 270 publications

Innovative chemical synthesis and conformational hints on the lipopeptide liraglutide

Innovative chemical synthesis and conformational hints on the lipopeptide liraglutide

Single and multiple peptide γ-turns: literature survey and recent progress

Heterochiral Ala/(αMe)Aze sequential oligopeptides: Synthesis and conformational study

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