Direct Spectroscopic Evidence of Hyperconjugation Unveils the Conformational Landscape of Hydrazides

Gloaguen, Éric; Brenner, V.; Alauddin, Mohammad; Tardivel, B.; Mons, Michel; Zehnacker‐Rentien, Anne; Declerck, Valérie; Aitken, David J.

doi:10.1002/ange.201407801

Cited by 9 publications

(3 citation statements)

References 26 publications

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“…Comparison between experiments and theory is not only mandatory for proposing a basic interpretation, but is also at the heart of several of the most outstanding outcomes in the field. 72,74,103,113,133,134,141,144,150,152,153,[157][158][159][160]162,163,181,203,218,219,241,284,301,314,334,387,391,423,517 Nowadays, quantum chemistry suites are often sophisticated black boxes: even if an in-depth rationalization of the underlying phenomena is not easy to extract from calculations, they provide experimentalists with a reliable and relevant prediction of some of the experimental observables in the ground electronic state, like vibrational modes. The situation is more contrasted as far as the electronic structure and dynamical properties of the excited states of aromatic residues are concerned.…”

Section: Experimental Data Vs Theoretical Predictionsmentioning

confidence: 99%

Neutral Peptides in the Gas Phase: Conformation and Aggregation Issues

et al. 2020

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Combined IR and UV laser spectroscopic techniques in molecular beams merged with theoretical approaches have proven to be an ideal tool to elucidate intrinsic structural properties on a molecular level. It offers the possibility to analyze structural changes by successively adding aggregation partners and thus an environment to a molecule. By this, it further makes these techniques a valuable starting point for a bottom-up approach in understanding the forces shaping larger molecular systems. This bottomup approach was successfully applied to neutral amino acids starting around the 1990s. Ever since experimental and theoretical methods developed further and investigations could be extended to larger peptide systems. Beyond, the review gives an introduction to secondary structures and experimental methods as well as a summary on theoretical approaches. Vibrational frequencies being characteristic probes of molecular structure and interactions are especially addressed. Archetypal biologically relevant secondary structures investigated by molecular beam spectroscopy are described and the influences of specific peptide residues on conformational preferences as well as the competition between secondary structures are discussed. Important influences like microsolvation or aggregation behaviour are presented. Beyond the linear α-peptides the main results of structural analysis on cyclic systems as well as on β-and γ-peptides are summarized. Overall, this contribution addresses current aspects of molecular beam spectroscopy on peptides and related species and provides molecular level insights into manifold issues of chemical and biochemical relevance. 45) , non-protected (cf. e.g. 46-48) and protected amino acids (cf. e.g. 49) up to dipeptide models (cf. e.g. 50).In this context, laser spectroscopic techniques combining IR and UV excitations, that one can consider as belonging to the so-called 'action spectroscopies', provide an isomer-selective method of choice to tackle the 87 ) or immunoglobulins (cf. e.g. 88), but they are also found in context with neurodegenerative diseases (cf. e.g. [89][90][91][92][93][94][95] and Section 12). A further structure associated with these diseases (cf. e.g. 96 ) is the β-helix, which presents a protein structure of several parallel β-strands in a helical arrangement with a frequently repetitive amino acid sequence. The structure is stabilized by H-bonds, sometimes ionic interactions or so called protein-protein interactions, which e.g. include electrostatic and hydrophobic effects. Further aspects of peptide structure in gas phase The role of protection groupsWith the unmodified N-and C-terminus amino acids and peptides can exhibit strong preferences for intramolecular H-bonds involving the N-and C-terminus, and can also form intermolecular H-bonds leading to polymer chains. Nevertheless, in a context where the description of the properties of a protein or a long peptide (with respect to its backbone) by smaller peptides is targeted, the introduction of protecting groups at the N-and...

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Section: Experimental Data Vs Theoretical Predictionsmentioning

confidence: 99%

Neutral Peptides in the Gas Phase: Conformation and Aggregation Issues

et al. 2020

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“…On the basis of the inputs obtained from the model systems containing OH, SH, and NH donors as well as O and S acceptors, it was extended to sulfur containing peptides to explore the role of SCHBs on local structures of the main chain induced by a Met or Cys residue. , The atomic scale information was obtained by gas phase spectroscopy of isolated model peptide chains. The approach was based on IR/UV double resonance spectroscopy of mass-selected jet-cooled molecules and their clusters, a technique very elegantly deployed on various model biomolecular systems as well as peptide chains. − It was observed that sulfur atoms in the side chain of methionine and cysteine are capable of forming strong amide NH···S H-bonds. In the methionine containing peptides (e.g., AcPheMetNH 2 ; in short FM) NH···S H-bonds were surprisingly found to be the strongest among other H-bonds (NH···OC and NH···π H-bonds) .…”

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confidence: 99%

Critical Assessment of the Strength of Hydrogen Bonds between the Sulfur Atom of Methionine/Cysteine and Backbone Amides in Proteins

Mundlapati

Ghosh

Bhattacherjee

et al. 2015

J. Phys. Chem. Lett.

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Gas-phase vibrational spectroscopy, coupled cluster (CCSD(T)), and dispersion corrected density functional (B97-D3) methods are employed to characterize surprisingly strong sulfur center H-bonded (SCHB) complexes between cis and trans amide NH and S atom of methionine and cysteine side chain. The amide N-H···S H-bonds are compared with the representative classical σ- and π-type H-bonded complexes such as N-H···O, N-H···O═C and N-H···π H-bonds. With the spectroscopic, theoretical, and structural evidence, amide N-H···S H-bonds are found to be as strong as the classical σ-type H-bonds, despite the smaller electronegativity of sulfur in comparison to oxygen. The strength of backbone-amide N-H···S H-bonds in cysteine and methionine containing peptides and proteins are also investigated and found to be of similar magnitudes as those observed in the intermolecular model complexes studied in this work. All such SCHBs also confirm that the electronegativities of the acceptors are not the sole criteria to predict the H-bond strength.

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“…In general, there are two opposing hyperconjugation interactions which affect the C=O stretching frequency of the ester carbonyl group . Additionally, the n→π* interaction, which is present only in the cis conformer but not in the trans conformer of PhOAc or PhOF, can affect the hyperconjugation interactions and hence the C=O stretching frequency.…”

Section: Resultsmentioning

confidence: 99%

Steric as well as n→π* Interaction Controls the Conformational Preferences of Phenyl Acetate: Gas‐phase Spectroscopy and Quantum Chemical Calculations

Singh

Panwaria

Mishra

et al. 2019

Chemistry An Asian Journal

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Herein, we report that the conformational preference of phenyla cetate is governed by steric effect and n! p*i nteraction. Conformation-specifice lectronic and IR spectroscopy combined with quantum chemistry calculations confirm the presence of only the cis conformer of phenyl acetate in the experiment. The cis conformer of phenyl acetate hasn !p*i nteraction betweent he lone-pair electrons on the carbonyl oxygen atom and the p*o rbitals of the phenyl group. The n!p*i nteraction is absent in the trans conformer whichh as additional steric repulsion between the methyl group and phenyl ring. The trans conformer is higher in energyt han the cis conformer by % 3kcal mol À1 .W eh ave found the effect of methyl substitution on the strength of the n!p*i nteraction, steric repulsion, and hyperconjugation in phenyla cetate. The red-shift observed in the cis conformer of phenyl acetate with respect to the trans conformer is affected due to the influence of the methyl substituent on the strength of the n!p*i nteraction as well as hyperconjugation.T he present result demonstrates that the introduction of abulkiersubstituent can induce steric as wellase lectronic control to reduce conformational heterogeneity of a molecular system. Understanding the effect of bulkiers ubstituents to promote defined conformations having specific non-covalent interactions may have implicationi nb etter perception of the optimum structure and function of biomolecules as well as recognition of drugs by biomolecules.[a] Dr.

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Direct Spectroscopic Evidence of Hyperconjugation Unveils the Conformational Landscape of Hydrazides

Cited by 9 publications

References 26 publications

Neutral Peptides in the Gas Phase: Conformation and Aggregation Issues

Neutral Peptides in the Gas Phase: Conformation and Aggregation Issues

Critical Assessment of the Strength of Hydrogen Bonds between the Sulfur Atom of Methionine/Cysteine and Backbone Amides in Proteins

Steric as well as n→π* Interaction Controls the Conformational Preferences of Phenyl Acetate: Gas‐phase Spectroscopy and Quantum Chemical Calculations

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