Vibrational and chiroptical spectroscopic characterization of γ‐turn model cyclic tetrapeptides containing two β‐Ala residues

Vass, Elemér; Májer, Zsuzsa; Kőhalmy, Krisztina; Hollósi, Miklós

doi:10.1002/chir.20831

Cited by 21 publications

(41 citation statements)

References 40 publications

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“…The presence of the positive band at 218 and 222 nm could be explained by the n-π* transition occurred within D-amino acids ( Vass et al, 2001 ). Moreover, this band might also be due to an unconventional turn conformation adopted by the peptide cycle of fengycin ( Vass et al, 1998 , 2001, 2003 , 2010 ). Another characteristic of the fengycin CD spectrum is the presence of negative bands at 206 and 211 nm, might be corresponding to the π-π* transition occurring within peptide bonds and is compatible with the presence of β sheet conformations.…”

Section: Resultsmentioning

confidence: 99%

Purification, biochemical characterization and self-assembled structure of a fengycin-like antifungal peptide from Bacillus thuringiensis strain SM1

et al. 2013

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An antifungal lipopeptide fengycin, producing strain SM1 was isolated from farm land soil sample and identified as Bacillus thuringiensis strain SM1 by using 16S rDNA analysis. Fengycin detected in the culture extract was further purified using HPLC and showed a molecular mass of 1492.8 Da by MALDI-TOF-MS analysis. Purified fengycin was allowed to construct their self-assembled structure onto a hydrophobic surface showing a clear improvement of antibacterial activity. In self-assembly, fengycin adapts a spherical micelle core shell like structure. Self-assembled fengycin may be a successful antimicrobial compound modifying its action from confined antifungal function. Besides it can open up a new area of research in supramolecular lipopeptide based compound making. This can revealed the mode of action of this unique self-assembled structure to fully evaluate its potential for use as an antimicrobial drug to control the emergence of bacterial infection.

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Section: Resultsmentioning

confidence: 99%

Purification, biochemical characterization and self-assembled structure of a fengycin-like antifungal peptide from Bacillus thuringiensis strain SM1

et al. 2013

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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%

“…A comparison of the spectra of the tripeptide 6 in the solid state (Figure ) and in solution (Figure ) strongly suggests that the 3260 cm −1 band (present in solution, but missing in the solid state) is related to an intramolecularly H‐bonded γ‐turn conformation . Indeed, the intramolecularly H‐bonded NH group of the β‐turn in the solid state must necessarily be associated to one of the two bands at 3354 and 3315 cm −1 .…”

Section: Resultsmentioning

confidence: 97%

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 spectra of the different secondary structures (periodic and aperiodic ordered; and unordered conformations) are well documented . The ECD study of the peptides in water and TFE ( α ‐helix‐promoting and membrane‐mimicking solvent) can help in understanding the conformational stability and the solvent sensitivity of peptides ; in addition, it can be useful at structure–function investigations.…”

Section: Resultsmentioning

confidence: 99%

Characterization of desmoglein-3 epitope region peptides as synthetic antigens: analysis of theirin vitroT cell stimulating efficacy, cytotoxicity, stability, and their conformational features

et al. 2015

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Oligopeptides, representing B-and/or T-cell epitope(s) are promising candidates as future synthetic antigens for studying human autoimmune disorders. Synthetic peptides could be as efficient in inducing in vitro T-cell responses as recombinant proteins. We have studied desmoglein 3 (Dsg3) peptides representing T-cell epitope regions to determine their capability to induce in vitro T-cell response and to analyze the influence of their solution conformation.The design of synthetic peptides used in this study was based on the previously described Dsg3 T-cell epitope regions and resulted in new N-terminally truncated versions. The peptides were prepared on solid phase and chemically characterized. In order to establish structureactivity relationship, the solution conformation of the synthetic peptides has been investigated using ECD spectroscopy. The in vitro T-cell stimulating efficacy as well as in vitro cytotoxicity and stability of the peptides have been determined on peripheral blood mononuclear cells (PBMC) isolated from whole blood of Pemphigus vulgaris (PV) patients and also from healthy donors. After 20 hours stimulation the IFN-γ content of the supernatants was measured by ELISA. Our data suggested that the in vitro IFN-γ production of PBMC culture derived from healthy donors and PV patients induced by synthetic peptides as antigens are markedly different. Comparative analysis of in vitro activity and the capability of oligopeptides to form ordered or unordered secondary structure was performed. We measured different in vitro T-cell stimulating activity on PBMC derived from patients and healthy donors, especially with synthetic peptides bearing high solvent sensibility which might suggest backbone flexibility.

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Vibrational and chiroptical spectroscopic characterization of γ‐turn model cyclic tetrapeptides containing two β‐Ala residues

Cited by 21 publications

References 40 publications

Purification, biochemical characterization and self-assembled structure of a fengycin-like antifungal peptide from Bacillus thuringiensis strain SM1

Purification, biochemical characterization and self-assembled structure of a fengycin-like antifungal peptide from Bacillus thuringiensis strain SM1

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

Characterization of desmoglein-3 epitope region peptides as synthetic antigens: analysis of theirin vitroT cell stimulating efficacy, cytotoxicity, stability, and their conformational features

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