Cyclo(<scp>l</scp>‐propyl‐<scp>l</scp>‐N‐methylphenylalanyl) Conformation in solution and in the crystal

Budêšínský, Miloś; Symerský, J.; Ječný, J.; Hecke, Jeroen Van; Hosten, N.; Anteunis, M.; Borremans, Frans

doi:10.1111/j.1399-3011.1992.tb00781.x

Cited by 10 publications

(2 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[88,89] The analysis of the J(NH, a H) vicinal couplings and the resultant f angles in [D 6 ]DMSO are summarized in Table 5. In most cases NMR spectroscopy can monitor the conformation of a cyclic dipeptide, and verify theoretical structural predictions.…”

Section: Nmr Resultsmentioning

confidence: 99%

Three Types of Induced Tryptophan Optical Activity Compared in Model Dipeptides: Theory and Experiment

et al. 2012

View full text Add to dashboard Cite

The tryptophan (Trp) aromatic residue in chiral matrices often exhibits a large optical activity and thus provides valuable structural information. However, it can also obscure spectral contributions from other peptide parts. To better understand the induced chirality, electronic circular dichroism (ECD), vibrational circular dichroism (VCD), and Raman optical activity (ROA) spectra of Trp-containing cyclic dipeptides c-(Trp-X) (where X = Gly, Ala, Trp, Leu, nLeu, and Pro) are analyzed on the basis of experimental spectra and density functional theory (DFT) computations. The results provide valuable insight into the molecular conformational and spectroscopic behavior of Trp. Whereas the ECD is dominated by Trp π-π* transitions, VCD is dominated by the amide modes, well separated from minor Trp contributions. The ROA signal is the most complex. However, an ROA marker band at 1554 cm(-1) indicates the local χ(2) angle value in this residue, in accordance with previous theoretical predictions. The spectra and computations also indicate that the peptide ring is nonplanar, with a shallow potential so that the nonplanarity is primarily induced by the side chains. Dispersion-corrected DFT calculations provide better results than plain DFT, but comparison with experiment suggests that they overestimate the stability of the folded conformers. Molecular dynamics simulations and NMR results also confirm a limited accuracy of the dispersion-DFT model in nonaqueous solvents. Combination of chiral spectroscopies with theoretical analysis thus significantly enhances the information that can be obtained from the induced chirality of the Trp aromatic residue.

show abstract

Section: Nmr Resultsmentioning

confidence: 99%

Three Types of Induced Tryptophan Optical Activity Compared in Model Dipeptides: Theory and Experiment

et al. 2012

View full text Add to dashboard Cite

show abstract

“…It is well-documented that when there is an aromatic group in the cyclic dipeptide the DKP ring will stay in a boat-shaped conformation with the aromatic group folded over the DKP ring. 38,39 The intramolecular dipole−induced dipole interaction between the DKP ring and the aromatic π electrons makes this structure energetically favored. 39 We propose that the transition state resembles the product (a "late" transition state), and the free energy barrier to reach this transition state is lowered by the interaction between the benzyl group and the DKP ring as it forms.…”

Section: Determination Of Penultimate Proline Configurationmentioning

confidence: 99%

Influence of N Terminus Amino Acid on Peptide Cleavage in Solution through Diketopiperazine Formation

Zhang

Hales

Clemmer

2022

J. Am. Soc. Mass Spectrom.

View full text Add to dashboard Cite

Diketopiperazine (DKP) formation is an important degradation pathway for peptides and proteins. It can occur during synthesis and storage in either solution or the solid state. The kinetics of peptide cleavage through DKP formation have been analyzed for the model peptides Xaa1-Pro2-Gly4-Lys7 [Xaa = Gln, Glu, Lys, Ser, Phe, Trp, Tyr, Cha (β-cyclohexylalanine), Aib (α-aminoisobutyric acid), Gly, and Val] at multiple elevated temperatures in ethanol with ion mobility spectrometry–mass spectrometry (IMS–MS). When Xaa is an amino acid with a charged or polar side chain, degradation is relatively fast. When Xaa is an amino acid with a nonpolar alkyl side chain, the peptide is relatively stable. For these peptides, a bulky group on the α carbon speeds up dissociation, but the kinetic effects vary in a complicated manner for bulky groups on the β or γ carbon. Peptides where Xaa has a nonpolar aromatic side chain show moderate dissociation rates. The stability of these peptides is a result of multiple factors. The reaction rate is enhanced by (1) the stabilization of the late transition state through the interaction of an aromatic ring with the nascent DKP ring or lowering the activation energy of nucleophilic attack intermediate state through polar or charged residues and (2) the preference of the cis proline bond favored by the aromatic N-terminus. The number of unseen intermediates and transition state thermodynamic values are derived for each peptide by modeling the kinetics data. Most of the transition states are entropically favored (ΔS ⧧ ∼ −5 to +31 J·mol–1·K–1), and all are enthalpically disfavored (ΔH ⧧ ∼ 93 to 109 kJ·mol–1). The Gibbs free energy of activation is similar for all of the peptides studied here (ΔG ⧧ ∼ 90–99 kJ·mol–1).

show abstract

Crystal structures of peptides and modified peptides

Marraud

Aubry

1996

Biopolymers

View full text Add to dashboard Cite

The X‐ray diffraction experiments on peptides and related molecules which have been carried out in Western Europe, except Italy, in the last eight years are reviewed. The crystal structures of some bioactive peptides such as Leu‐enkephalin (a neurotransmitter), cyclosporin A (an immunomodulator in both the free and protein‐bound state), balhimycin (an antibiotic) and octreotide (a somatostatin analogue) are briefly presented. Crystallized N‐ and C‐protected model peptides have given an insight into the folding tendency and folding modes depending on the peptide sequences. The crystal structures of various pseudopeptide molecules reveal how the three‐dimensional structure of peptide analogues can be modulated by substituting non‐peptide groups for the peptide bond. A few examples of structural mimetics of the β‐ and γ‐turns, and of templates for α‐helix induction are also presented. © 1996 John Wiley & Sons, Inc.

show abstract

Cyclo(l‐propyl‐l‐N‐methylphenylalanyl) Conformation in solution and in the crystal

Cited by 10 publications

References 25 publications

Three Types of Induced Tryptophan Optical Activity Compared in Model Dipeptides: Theory and Experiment

Three Types of Induced Tryptophan Optical Activity Compared in Model Dipeptides: Theory and Experiment

Influence of N Terminus Amino Acid on Peptide Cleavage in Solution through Diketopiperazine Formation

Crystal structures of peptides and modified peptides

Contact Info

Product

Resources

About