Vibrational circular dichroism studies of molecular conformation and association of dipeptides

Miyazawa, Mitsuhiro; Kyogoku, Yoshimasa; Sugeta, Hiromu

doi:10.1016/0584-8539(94)e0061-e

Cited by 17 publications

(11 citation statements)

References 19 publications

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“…After the curve-fitting procedure (see Fig. 2) their positions are at =3448,3431 and 3413 cm-' (for Ac-Phe-NHMe 3447, 3421 and 3410 cm-') with the average A V , ,~ 20, 25 and 35 cm-', respectively. This proves that there are two N-H groups free and that some part of the N'-H' groups is involved with the C5 structure as proposed by numerous IR studies in CCI4 and CHC1, solutions (38,42,43). Only two v,(N-H) bands occur for unsaturated analogs, however, at ~3 4 5 3 and 3412 cm-' (for Ac-(a-APhe-NHMe at 3451 and 3401 cm-I) with the average AvIR 25 and 34 cm-'.…”

Section: Conformation Of Ac-axaa-nhmesupporting

confidence: 67%

“…3) and 3342-3346 cm-' for unsaturated and saturated compounds, respectively. Absorption in this spectral region is assignable to the v,(N2-H2) mode of a C7 conformer (19, 20,41) and/or the v,(N-H) modes of some associates (38). On dilution to 104 M, the band vanished for Ac-AXaa-NHMe 3379 3466 1698 1663 1674a 1678 1676 1674 1671 1685a 1496 1536a 1631 Ac-(Z)-AAbu-NHMe Ac-(9-ALeu-NHMe Ac-(a-APhe-NHMe Ac-AVal-NHMe Ac-Ala-NHMe and diminished meaningfully for Ac-Xaa-NHMe.…”

Section: Ftir Spectramentioning

confidence: 99%

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Conformational investigation of α, β‐dehydropeptides. VIII.*N‐Acetyl‐α, β‐dehydroamino acid N'‐methylamides: conformation and electron density perturbation from infrared and theoretical studies

Broda

Rzeszotarska

Smelka

et al. 1997

The Journal of Peptide Research

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The Fourier transform infrared spectra are analyzed in the regions of vs(N‐H), amide I, amide II and vs(Cα=Cβ) bands for a series of Ac‐ΔXaa‐NHMe, where ΔXaa =ΔAla, (Z)‐ΔAbu, (Z)‐ΔLeu, (Z)‐ΔPhe and AVal, to determine the predominant solution conformation of these α, β‐dehydropeptide‐related molecules and the electron distribution perturbation in their amide bonds. The measurements were performed in dichloromethane (DCM). To confirm and rationalize the assignments, the spectra of the respective series of saturated Ac‐Xaa‐NHMe, recorded in DCM, and the spectra of these two series of unsaturated and saturated compounds, recorded in acetonitrile, were examined. To help interpret the spectroscopic results, the equilibrium geometrical parameters for some selected amides were used. These were optimized with ab initio methods in the 6‐31G** basis set. Each of the dehydroamides studied adopted a C5 structure, which in Ac‐ΔAla‐NHMe is fully extended and accompanied by the strong C5 hydrogen bond. Interaction with the Cα=Cβ bond lessened the amidic resonance within each of the flanking amide groups. The N‐terminal C=O bond was noticeably shorter, both amide bonds were longer than the corresponding bonds in the saturated entities and the N‐terminal amide system was distorted. Ac‐ΔAla‐NHMe constituted an exception. Its C‐terminal amide bond was shorter than the standard one and both amide systems were prototypically planar.

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Section: Conformation Of Ac-axaa-nhmesupporting

confidence: 67%

Section: Ftir Spectramentioning

confidence: 99%

Conformational investigation of α, β‐dehydropeptides. VIII.*N‐Acetyl‐α, β‐dehydroamino acid N'‐methylamides: conformation and electron density perturbation from infrared and theoretical studies

Broda

Rzeszotarska

Smelka

et al. 1997

The Journal of Peptide Research

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“…They include ab initio calculations of VCD (92) and ROA (109) of N-acetyl-L-alanine Nmethylamide, empirical ROA studies of simple alanyl peptides (171,172), and VCD studies in the NH-stretching region of a family of blocked alanyl peptides (173). A VCD study of the conformation of alanyl and leucyl tripodal peptides has appeared (174) in which the sense of twist of a threefold symmetric propeller pattern stabilized by inter-chain hydrogen bonding was deduced by using a coupled oscillator formalism (175).…”

Section: Applications Of Voamentioning

confidence: 99%

INFRARED AND RAMAN VIBRATIONAL OPTICAL ACTIVITY: Theoretical and Experimental Aspects

Nafie

1997

Annu. Rev. Phys. Chem.

312

217

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Advances in the field of vibrational optical activity (VOA) are reviewed over the past decade. Topics are surveyed with an emphasis on the theoretical and instrumental progress in both vibrational circular dichroism (VCD) and Raman optical activity (ROA). Applications of VOA to stereochemical and biological problems are reviewed, with a bias toward new kinds of experiments made possible by theoretical and instrumental advances. In the field of VCD, the most notable advances have taken place in the quality and size of ab initio calculations of VOA intensities and in the quality of step-scan Fourier transform instrumentation. For ROA, the most dramatic progress has occurred in the areas of theoretical formulation and high-throughput instrumentation. Applications of VOA now include all major classes of biological and pharmaceutical molecules. VOA's importance as a diagnostic tool will likely grow as the control of molecular chirality increases in research and industrial areas.

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“…At this point, we apply transformations [7] to [7ٞ] (taking into account the explicit forms of the transformations S 1 and S 2 in [8] to [8Љ] and [9] to [9Љ]) to the electric dipole moment operator µ and magnetic dipole moment operator m. We report these expressions in the Appendix. Finally, one can take the following transition moments:…”

Section: Contact Transformation Theorymentioning

confidence: 99%

Theoretical and experimental studies for the interpretation of vibrational circular dichroism spectra in the CH-stretching overtone region

2000

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Two theoretical models for the interpretation of the existing data of CH‐stretching overtones' vibrational circular dichroism data are presented. The first model is based on the quantum mechanical Van Vleck contact transformation theory and is applied to the full vibrational problem, the second is based on classical trajectories calculations, by which we treat a simplified three‐degrees of freedom Hamiltonian. The latter allows one to derive a qualitative but efficacious picture of the behavior of coupled anharmonic oscillators. In this framework, we analyze the Poincaré Surfaces of Section, and calculate the Fourier Cross Spectra of coupled CH‐stretchings. Values for the harmonic frequencies and anharmonicities are derived from absorption spectra in the near infrared on partially deuterated compounds. The effect of large amplitude, low‐frequency puckering or twisting modes on the ensemble of coupled CH‐stretching is taken into account. Chirality 12:180–190, 2000. © 2000 Wiley‐Liss, Inc.

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Vibrational circular dichroism studies of molecular conformation and association of dipeptides

Cited by 17 publications

References 19 publications

Conformational investigation of α, β‐dehydropeptides. VIII.*N‐Acetyl‐α, β‐dehydroamino acid N'‐methylamides: conformation and electron density perturbation from infrared and theoretical studies

Conformational investigation of α, β‐dehydropeptides. VIII.*N‐Acetyl‐α, β‐dehydroamino acid N'‐methylamides: conformation and electron density perturbation from infrared and theoretical studies

INFRARED AND RAMAN VIBRATIONAL OPTICAL ACTIVITY: Theoretical and Experimental Aspects

Theoretical and experimental studies for the interpretation of vibrational circular dichroism spectra in the CH-stretching overtone region

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