Temperature dependence of peptide NH chemical shifts in benzene: Delineation of solvent‐shielded and exposed amide protons

Venkatachalapathi, Y. V.; Balaram, Padmanabhan

doi:10.1002/bip.1981.360200313

Cited by 21 publications

(10 citation statements)

References 14 publications

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“…2). Similar experiments have been carried out for other Aib-containing peptides in DMSO-d6, (12,13,37,38) the results of which are consistent with the adoption of a 310-helical conformation by the Aib residue in these peptides.…”

Section: Assignment Of Nh Resonancessupporting

confidence: 81%

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Solution conformations of oligomers of α ‐aminoisobutyric acid°

Paterson

Stimson

Evans

et al. 1982

International Journal of Peptide and Protein Research

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The N‐acetyl(Aib)nN' ‐methylamides (with n= 1, 2 and 3) and the N‐acetyl‐(Aib)3 methyl ester have been synthesized using an oxazolone procedure. An experimental conformational analysis of this series of oligomers has been carried out in water, DMSO‐d6 and CDCI3 using n.m.r. techniques, and in chloroform using i.r. spectroscopy. Deuterium exchange rates of amide protons in DMSO‐d6 and the rates of change of these proton chemical shifts with temperature in water, DMSO‐d6 and CDCI3 indicate that the oligomeric N'‐methylamides adopt conformations that have no hydrogen bonds when n = 1, one hydrogen bond when n = 2, and two hydrogen bonds when n = 3, and that Ac(Aib)3OMe has a conformation with one hydrogen bond. An analysis of the N‐H stretching region of the i.r. spectra of these compounds in CHCI3 also suggests the existence of these conformational states. These data imply that the peptides adopt the 310‐helical and not the α‐helical conformation in solution. This conclusion supports the hypothesis that the Aib residue has asymmetric geometry at the Cα atom in solution, similar to that reported in the literature for the crystalline state.

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Section: Assignment Of Nh Resonancessupporting

confidence: 81%

“…There have been few studies on the temperature dependence of NH chemical shifts of peptides in nonpolar solvents (12,(38)(39)(40) with which to compare the results that we obtained in deuterochloroform, shown in Table 1.…”

Section: Assignment Of Nh Resonancesmentioning

confidence: 90%

Solution conformations of oligomers of α ‐aminoisobutyric acid°

Paterson

Stimson

Evans

et al. 1982

International Journal of Peptide and Protein Research

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“…Of the remaining residues, Leu(1) and Val(8) NH groups showed relatively lower temperature dependences, suggesting a greater degree of solvent shielding, consistent with their involvement of inter-strand interaction in the proposed β-hairpin conformation. It should be noted that the temperature coefficients in aromatic solvents, such as C 6 D 6 must be interpreted with caution because of specific solvation effects 25. The observation of a β-hairpin conformation in crystals23 with nearly ideal interstrand hydrogen bonding lends additional support to the above interpretation of NMR data.Conformation in CDCl 3 .…”

mentioning

confidence: 75%

β-Hairpin nucleation by Pro-Gly β-turns. Comparison of D-Pro-Gly and L-Pro-Gly sequences in an apolar octapeptide

Raghothama¹,

Awasthi²,

Balaram³

1998

J. Chem. Soc., Perkin Trans. 2

105

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The solution conformation of the synthetic octapeptide Boc-Leu-Val-Val-D-Pro-Gly-Leu-Val-Val-OMe 1 and Boc-Leu-Val-Val-Pro-Gly-Leu-Val-Val-OMe 2 have been investigated in organic solvents by NMR spectroscopy. Peptide 1 adopts well-defined -hairpin conformations in CDCl 3 , C 6 D 6 and (CD 3 ) 2 SO, nucleated by a D-Pro-Gly Type IIЈ -turn, as demonstrated by the observation of characteristic nuclear Overhauser effects (NOEs) between backbone protons and solvent shielding of NH groups involved in cross-strand hydrogen bonding. Chemical shifts and coupling constants provide further support for the -hairpin conformation, which is consistent with the observation of a single negative circular dichroism band at 216 nm in methanol. In peptide 2, there is no characteristic interstrand NOE observed in (CD 3 ) 2 SO, while in CDCl 3 pronounced aggregation results in line broadening. The observation of a low temperature coefficient for the Leu(6)NH proton favours a population of Pro-Gly Type II -turn conformations. These results suggest that in short peptide sequences, the precise nature of the -turn is critical for hairpin formation, with Type IIЈ -turns being particularly effective.

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“…25 In these peptides there was little evidence for aggregation in (CD&SO over the concentration range 10-2-10-3M. In CDC13, peptide association occurs at concentrations of -lo-".…”

Section: Aib-leu-aib-gly-leu-aib-pro-val-aib-aib-ome30 and Z-(aib-prmentioning

confidence: 94%

Stereochemistry of α‐aminoisobutyric acid peptides in solution: Helical conformations of protected decapeptides with repeating Aib‐L‐Ala and Aib‐L‐Val sequences

Vijayakumar

Balaram

1983

Biopolymers

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SynopsisThe decapeptides Boc-(Aib-L-Ala)s-OMe and Boc-(Aib-L-Val)s-OMe have been studied by 270-MHz lH-nmr in CDCl3 and (CD&SO solutions. Intramolecular hydrogen-bonded NH groups have been delineated using the temperature and solvent dependence of the NH chemical shifts and differential broadening of the NH resonances, induced by addition of a nitroxide radical. Both peptides have eight solvent-shielded NH groups, suggesting that dlo-helical conformations are maintained in the two solvents. In alternating Aib-X sequences, the Aib residues appear to play a dominant role in determining the preferred conformations, overriding the intrinsic stereochemical preferences of the X residues.

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Temperature dependence of peptide NH chemical shifts in benzene: Delineation of solvent‐shielded and exposed amide protons

Cited by 21 publications

References 14 publications

Solution conformations of oligomers of α ‐aminoisobutyric acid°

Solution conformations of oligomers of α ‐aminoisobutyric acid°

β-Hairpin nucleation by Pro-Gly β-turns. Comparison of D-Pro-Gly and L-Pro-Gly sequences in an apolar octapeptide

Stereochemistry of α‐aminoisobutyric acid peptides in solution: Helical conformations of protected decapeptides with repeating Aib‐L‐Ala and Aib‐L‐Val sequences

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