The rotamerization of conformers of glycine isolated in inert gas matrices. An infrared spectroscopic study

Reva, Igor; Plokhotnichenko, A. M.; Stepanian, S. G.; Ivanov, А. Yu.; Radchenko, E. D.; Sheina, G. G.; Blagoi, Yuri P.

doi:10.1016/0009-2614(95)90630-b

Cited by 109 publications

(106 citation statements)

References 30 publications

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“…If the barriers are about or lower than 1 kcal/mol the conformers relax to the lowest configuration even in a matrix as cold as 10 K. Due to the effects of conformer relaxation, there are few examples of using matrix spectra to acquire ⌬H values, as was done for glycine. 21 The rate of relaxation was found to increase with matrix temperature. It also depends on the matrix material and increases for the series Ar, Kr, Xe.…”

Section: ͑4͒mentioning

confidence: 96%

Using He droplets for measurements of interconversion enthalpy of conformers in 2-chloroethanol

Skvortsov

Vilesov

2009

The Journal of Chemical Physics

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2-chloroethanol molecules having temperature from 300 to 600 K have been captured by helium droplets and the infrared spectra of the O–H and C–H stretching bands of the embedded molecules have been obtained. The intensity ratio of the bands due to trans and gauche conformers of the molecules follows the Arrhenius dependence, giving the enthalpy of conformers interconversion of 1.1 kcal/mol. It is concluded that the abundance ratio of the conformers, which are at equilibrium in the gas phase, remains unchanged upon the rapid cooling of the molecules in the helium droplets.

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Section: ͑4͒mentioning

confidence: 96%

Using He droplets for measurements of interconversion enthalpy of conformers in 2-chloroethanol

Skvortsov

Vilesov

2009

The Journal of Chemical Physics

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“…The relatively small barrier that we calculate for III→ I interconversion is more consistent with the upper-bound estimate of 5.8 kJ/ mol obtained from matrix annealing experiments. 18 The C-N torsional potential curve ͑right panel͒ has minima at 3 = 0°for conformer I and at 3 = ± 105°for the symmetric, nonplanar geometries of conformer IV. Comparison of the potential curves shown in Fig.…”

Section: A Torsional Potential and Eigenstatesmentioning

confidence: 99%

“…29 Extensive electronic structure theory studies predict glycine to have numerous stable conformers arising from internal rotation about its three torsional modes, [11][12][13] but only three of these conformers have been conclusively observed in experiment. [18][19][20][21][22][23] In the current paper, we present a theoretical study of collision-induced conformational changes in glycine and consider evidence for the population of a fourth conformer. Figure 1͑a͒ presents the experimentally observed conformers of glycine and their thermal populations at 438 K, as determined from the integrated ͑C v O͒ bands of the infrared vibrational spectrum taken in a low-temperature neon matrix.…”

Section: Introductionmentioning

confidence: 99%

Collision-induced conformational changes in glycine

Miller

Clary

Meijer

2005

The Journal of Chemical Physics

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We present quantum dynamical calculations on the conformational changes of glycine in collisions with the He, Ne, and Ar rare-gas atoms. For two conformer interconversion processes ͑III→ I and IV→ I͒, we find that the probability of interconversion is dependent on several factors, including the energy of the collision, the angle at which the colliding atom approaches the glycine molecule, and the strength of the glycine-atom interaction. Furthermore, we show that attractive interactions between the colliding atom and the glycine molecule catalyze conformer interconversion at low collision energies. In previous infrared spectroscopy studies of glycine trapped in rare-gas matrices and helium clusters, conformer III has been consistently observed, but conformer IV has yet to be conclusively detected. Because of the calculated thermodynamic stability of conformer IV, its elusiveness has been attributed to the IV→ I conformer interconversion process. However, our calculations present little indication that IV→ I interconversion occurs more readily than III→ I interconversion. Although we cannot determine whether conformer IV interconverts during experimental Ne-and Ar-matrix depositions, our evidence suggests that the conformer should be present in helium droplets. Anharmonic vibrational frequency calculations illustrate that previous efforts to detect conformer IV may have been hindered by the overlap of its IR-absorption bands with those of other conformers. We propose that the redshifted symmetric −CH 2 stretch of conformer IV provides a means for its conclusive experimental detection.

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Section: Introductionmentioning

confidence: 98%

“…The first MI-IR spectroscopic investigations on amino acid residues were performed by Grenie et al (1970), who studied glycine (Gly) in an Ar matrix. Since then Gly (Grenie and Garrigou-Lagrange1972;Reva et al 1995;Stepanian et al 1998a;Ivanov et al 1997Ivanov et al , 1999Bazsó et al 2012a, b) and many other amino acids were thoroughly studied by MI-IR spectroscopy, including alanine (Rosado et al 1997;Stepanian et al 1998b;Lambie et al 2003;Bazsó et al 2013), valine (Stepanian et al 1999), leucine (Sheina et al 1988), isoleucine (Boeckx and Maes 2012a), proline (Reva et al 1994;Stepanian et al 2001), serine (Lambie et al 2004;Jarmelo et al 2005;Jarmelo et al 2006), phenylalanine (Kaczor et al 2006), tyrosine (Ramaekers et al 2005), tryptophan (Kaczor et al 2007), cysteine (Dobrowolski et al 2007), asparagine (Boeckx and Maes 2012b), lysine (Boeckx and Maes 2012c), and β-alanine (Rosado et al 1997;Dobrowolski et al 2008). In a step towards understanding the structure and folding of peptides, protected amino acids, the smallest peptide models, were also investigated by this technique, including N-formylglycine (For-Gly, Wierzejewska and OlbertMajkut 2009), N-acetylglycine (Ac-Gly, Boeckx and Maes2012d), N-acetylalanine (Ac-Ala, Boeckx and Maes 2012e), N-acetyproline (Ac-Pro, Boeckx et al 2011), N-acetylcysteine (Ac-Cys, Boeckx et al 2010), Nacetyl-N′-methyl-glycine-amide (Ac-Gly-NHMe, Grenie et al1975;Pohl et al 2007), N-acetyl-N′-methyl-Lalanine-amide (Ac-L-Ala-NHMe, Grenie et al 1975;…”

Section: Introductionmentioning

confidence: 99%

Foldamers of β-peptides: conformational preference of peptides formed by rigid building blocks. The first MI-IR spectra of a triamide nanosystem

et al. 2013

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IntroductionAlthough dynamic on a large timescale of motion, some biologically active polyamide nanosystems adopt welldefined 3D structures in a time average manner, called as globular proteins; a given name reflecting to their overall shape. Other proteins called intrinsically unstructured or dynamic (IUP or IDP) are reluctant to present such an easy to characterize structural ensemble, nicknamed as proteins with random structures. Thus, proteins exist in most phases as conformational ensembles presenting lower, while in other environment higher time average deviation from their average 3D folds. The α-amino acid sequence modification of these inherently dynamic polyamide systems can lower, or increase the amplitude and frequency of such internal motion, making the protein fold less or more -mobile‖. The chemical constitution (α) and the stereochemistry (L) of proteogenic amino acid residues are under strict evolutional conservation. Unlike L-Proline, all the remaining 19 common residues in proteins have two adjacent backbone torsional angles, φ and ψ, of high rotational freedom followed by the inflexible ω. The scenario of two flexible followed by a fixed backbone torsional angles per residue determines primarily the folding ability of a proteogenic polypeptide. Cutting of a globular fold seldom results in secondary structural elements (e.g. α-helix, β-turn) of low internal dynamics! Typically the removal of any secondary structural element from its -natural environment‖ results in polypetides of very elevated internal dynamics, often characterized as unstructured subunits. However, bioengineering requires stable toolkits to design epitopes, matching complementary folds, individual foldamers, nano-lego elements etc. of traceable shape and of low internal mobility. Shedding light on folding and stability of secondary structural elements of peptides and proteins could help to design standalone foldamers. They could be composed of β-, α-and α/β-amino acid residues, the latter called chimera. A general expectation of foldamers is to present a single time average 3D-structure of lower internal dynamics over the large timescale of picoseconds to second. These fold optimized biocompatible and nonnatural peptides often have an increased proteolytic and metabolic stability and can fulfill diverse biological functions toward DNA, RNA, ATP, etc. The improved ability of β-peptides and thus β-foldamers to rapidly and spontaneously fold (

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The rotamerization of conformers of glycine isolated in inert gas matrices. An infrared spectroscopic study

Cited by 109 publications

References 30 publications

Using He droplets for measurements of interconversion enthalpy of conformers in 2-chloroethanol

Using He droplets for measurements of interconversion enthalpy of conformers in 2-chloroethanol

Collision-induced conformational changes in glycine

Foldamers of β-peptides: conformational preference of peptides formed by rigid building blocks. The first MI-IR spectra of a triamide nanosystem

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