Manifestation in the <sup>13</sup>C‐NMR spectra of two different molecular conformations of a cyclic pentapeptide

Wüthrich, Kurt; Tun‐Kyi, A.; Schwyzer, R.

doi:10.1016/0014-5793(72)80464-2

Cited by 74 publications

(21 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…It is seen that the corresponding CO and Cr resonances of cis and trans proline are separated by approximately 2 ppm and can thus be resolved readily. [16][17][18][19] The cis-trans equilibrium in the fully protonated form of the dipeptide is essentially independent of the solvent (Fig. 1).…”

Section: Resultsmentioning

confidence: 99%

See 1 more Smart Citation

Nmr studies of the molecular conformations in the linear oligopeptides H‐(L‐Ala)_n‐L‐Pro‐OH

Grathwohl¹,

Wüthrich²

1976

Biopolymers

138

View full text Add to dashboard Cite

SynopsisThe molecular conformations of the linear oligopeptides H-(t,-Ala)Iz -I.-Pro-OH, with n = 1 , 2 , and 3, have been investigated. ':IC nmr observation of the equilibrium between the cis and trans forms of the Ala-Pro peptide bond indicated the occurrence of nonrandom conformations in solutions of these flexible peptides. The formation of the nonrandom species containing the cis form of the Ala-Pro bond was found to depend on the deprotonation of the carboxylic acid group of proline, the solvent, and the ionic strength in aqueous solution. The influence of intramolecular hydrogen bonding on the relative conformational energies of the species containing the cis and trans Ala-Pro peptide bond was studied by comparison of the peptides H-(Ala), -Pro-OH with analogous molecules where hydrogen bond formation was excluded by the covalent structure. In earlier work a hydrogen bond between the protonated terminal carboxylic acid group and the carbonyl oxygen of the penultimate amino acid residue had been suggested to stabilize conformations including trans proline. For the systems described here this hypothesis can be ruled out, since the &:trans ratio is identical for molecules with methyl ester protected and free protonated terminal carboxylic acid groups of proline. Direct evidence for hydrogen bond formation between the deprotonated terminal carhoxylic acid group and the amide proton of the penultimate amino acid residue in the molecular species containing cis proline was obtained from 'H nmr studies. However, the the Ala-Pro bond was not affected by N-methylation of the penultimate amino acid residue, which prevents formation of this hydrogen bond. Overall the experimental observations lead to the conclusion that the relative energies of the peptide conformations including cis or trans proline are mainly determined by intramolecular electrostatic interactions. whereas in the molecules considered, intramolecular hydrogen bonding is a consequence of specific peptide backbone conformations rather than a cause for the occurrence of energetically favored species. Independent support for this conclusion was obtained from model considerations which indicated that electrostatic interactions between the terminal carboxylic acid group and the carbonyl oxygen of the penultimate amino acid residue could indeed account for the observed relative conformational energies of the species containing cis and trans proline. respectively.

show abstract

Section: Resultsmentioning

confidence: 99%

“…16 MHz on a Varian XL-100 spec-trometer, using 12-mm sample tubes. The relative concentrations of the cis and trans forms of the X-Pro peptide bonds were obtained from measurements of the peak heights of corresponding resonances in the two species.…”

Section: Methodsmentioning

confidence: 99%

Nmr studies of the molecular conformations in the linear oligopeptides H‐(L‐Ala)_n‐L‐Pro‐OH

Grathwohl¹,

Wüthrich²

1976

Biopolymers

138

View full text Add to dashboard Cite

show abstract

“…Measurement of cis content was made from peak intensities, assuming that cis and truns isomers had the same relaxation times and nuclear Overhauser enhancements [B] . The percentage of each isomer [3,4,6] could be measured on the 6, p or y carbons of proline in each spectrum. Results agreed within 1% in each spectrum.…”

Section: Cis-trans Isomerismmentioning

confidence: 99%

Carbon‐13 nuclear magnetic resonance studies on thyrotropin‐releasing factor and related peptides

et al. 1973

View full text Add to dashboard Cite

“…'3C chemical shifts (20), spin-lattice relaxation times of individual '3C species (21)(22)(23), and couplings between '3C-'H (24)(25)(26) and '3C-'3C (27)(28)(29) are potentially useful for conformational analysis of peptides. Chemical shifts of 13C resonances allow the detection in peptides of cis and trans isomerism about the amide bonds of proline residues (30)(31)(32)(33)(34) histidine residues (35); it has also been shown that the helixcoil transition of a polypeptide is accompanied by changes in chemical shifts (36)(37)(38). In addition, on formation of a hydrogen bond, downfield shifts of 0.3-0.7 ppm occur for carbonyl '3C resonances (31).…”

mentioning

confidence: 99%

Conformational Studies of Oxytocin, Lysine Vasopressin, Arginine Vasopressin, and Arginine Vasotocin by Carbon-13 Nuclear Magnetic Resonance Spectroscopy

Walter

Prasad

Deslauriers

et al. 1973

Proc. Natl. Acad. Sci. U.S.A.

View full text Add to dashboard Cite

Oxytocin, arginine vasopressin, lysine vasopressin, arginine vasotocin, as well as their cyclic and acyclic analogs, were studied by carbon-13 nuclear magnetic resonance spectroscopy in deuterium oxide and deuterated dimethylsulfoxide. Fourier-transformed spectra were obtained at 25. 16 MHz. The resonances of all carbon atoms have been assigned in both solvent systems; this includes tentative assignments of the carbonyl carbons. The spectra of arginine vasopressin and lysine vasopressin are essentially identical when compared in D20 or dimethylsulfoxide, but they differ from those of oxytocin. The spectrum of arginine vasotocin in D20 is intermediate between those of oxytocin and the vasopressins. These spectral differences are not only due to variations in constituent amino acids but are also a reflection of conformational differences of oxytocin, arginine vasotocin, and the vasopressins. All hormones are sensitive to changes in hydrogen ion concentration in both solvents; this was not observed with deamino analogs, which lack the terminal amino group.Conformational analysis of data from proton nuclear magnetic resonance ('H NMR) spectroscopy has contributed significantly to elucidation of the preferred solution conformations of oxytocin (1, 2) and lysine vasopressin ([Lys8]VP) (3-7). Nevertheless, the conformational analysis involves several approximations: (1) the relationship between the dihedral angle 0 (NH-CaH) and the measured three-bond coupling constant 3JHNCH (8, 9)-a spectral parameter most useful when considered in combination with potential energy maps (10, 11); (2)

show abstract

Manifestation in the ¹³C‐NMR spectra of two different molecular conformations of a cyclic pentapeptide

Cited by 74 publications

References 21 publications

Nmr studies of the molecular conformations in the linear oligopeptides H‐(L‐Ala)_n‐L‐Pro‐OH

Nmr studies of the molecular conformations in the linear oligopeptides H‐(L‐Ala)_n‐L‐Pro‐OH

Carbon‐13 nuclear magnetic resonance studies on thyrotropin‐releasing factor and related peptides

Conformational Studies of Oxytocin, Lysine Vasopressin, Arginine Vasopressin, and Arginine Vasotocin by Carbon-13 Nuclear Magnetic Resonance Spectroscopy

Contact Info

Product

Resources

About

Manifestation in the 13C‐NMR spectra of two different molecular conformations of a cyclic pentapeptide

Cited by 74 publications

References 21 publications

Nmr studies of the molecular conformations in the linear oligopeptides H‐(L‐Ala)n‐L‐Pro‐OH

Nmr studies of the molecular conformations in the linear oligopeptides H‐(L‐Ala)n‐L‐Pro‐OH

Carbon‐13 nuclear magnetic resonance studies on thyrotropin‐releasing factor and related peptides

Conformational Studies of Oxytocin, Lysine Vasopressin, Arginine Vasopressin, and Arginine Vasotocin by Carbon-13 Nuclear Magnetic Resonance Spectroscopy

Contact Info

Product

Resources

About

Manifestation in the ¹³C‐NMR spectra of two different molecular conformations of a cyclic pentapeptide

Nmr studies of the molecular conformations in the linear oligopeptides H‐(L‐Ala)_n‐L‐Pro‐OH

Nmr studies of the molecular conformations in the linear oligopeptides H‐(L‐Ala)_n‐L‐Pro‐OH