Estimating the relative populations of 310-helix and α-helix in Ala-rich peptides: a hydrogen exchange and high field NMR study

Millhauser, Glenn L.; Stenland, Chris; Hanson, P. J.; Bolin, Kimberly A.; Ven, F.J.M. van de

doi:10.1006/jmbi.1997.0923

Cited by 118 publications

(181 citation statements)

References 51 publications

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“…Once a 3 10 -helix is formed, conversion to an ␣-helix should be highly facilitated, both kinetically and thermodynamically. In fact, several peptides have been shown to exist in an equilibrium between the two types of helices both in water 107 and in nonpolar media. [108][109][110][111][112] However, for LQQLLQQLLQL and other peptides capable of forming amphipathic ␣-helices, 3 10 -helices are not amphipathic, and therefore may not be stable intermediates at interfaces.…”

Section: Resultsmentioning

confidence: 99%

Early events in the folding of an amphipathic peptide: A multinanosecond molecular dynamics study

1999

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Section: Resultsmentioning

confidence: 99%

Early events in the folding of an amphipathic peptide: A multinanosecond molecular dynamics study

1999

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“…This result is in good agreement with the published NMR data on the L-Val2 analog 4 39 of the same, fully 3 10 -helical, parent peptide 3, 38 and beautifully parallels that of an NMR study on an Ala-rich peptide, where an ␣-helical sequence was identified in the middle and short 3 10 -helical stretches at both termini. 61 A previous detailed structural investigation on an N ␣ -acylated octapeptide ester (equivalent to a heptapeptide alkylamide as far as its capability of intramolecular H-bond formation is concerned), characterized by seven Aib residues and a single C ␣ -trisubstituted ␣-amino acid (L-Leu6) near the C-terminus (2), unequivocally established the onset of a fully developed, rigid, regular 3 10 -helical conformation, [30][31][32][33][34][35] as observed in the -(Aib) 8 -homopeptide sequence (1). 36,37 Taken together, these findings support the view that, even in the case of a very high percentage of C ␣ -tetrasubstituted ␣-amino acids discussed here, the precise positioning of the single C ␣ -trisubstituted residue in the sequence may have a dramatic effect on the helical structure of the peptide backbone.…”

Section: Discussionmentioning

confidence: 97%

Factors governing 3₁₀‐helix vs α‐helix formation in peptides: Percentage of C^α‐tetrasubstituted α‐amino acid residues and sequence dependence

et al. 2002

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As an additional step toward the dissection of the factors responsible for the onset of 3(10)-helix vs alpha-helix in peptides, in this paper we describe the results of a three-dimensional (3D) structural analysis by x-ray diffraction of the N(alpha)-acylated heptapeptide alkylamide mBrBz-L-Iva-L-(alphaMe)Val-L-Abu-L-(alphaMe)Val-L-(alphaMe)Phe-L-(alphaMe)Val-L-Iva-NHMe characterized by a single (L-Abu3) C(alpha)-trisubstituted and six C(alpha)-tetrasubstituted alpha-amino acids. We find that in the crystal state this peptide is folded in a mixed helical structure with short elements of 3(10)-helix at either terminus and a central region of alpha-helix. This finding, taken together with the published NMR and x-ray diffraction data on the all C(alpha)-methylated parent sequence and its L-Val2 analog (also the latter heptapeptide has a single C(alpha)-trisubstituted alpha-amino acid) strongly supports the view that one C(alpha)-trisubstituted alpha-amino acid inserted near the N-terminus of an N(alpha)-acylated heptapeptide alkylamide sequence may be enough to switch a regular 3(10)-helix into an essentially alpha-helical conformation. As a corollary of this work, the x-ray diffraction structure of the N(alpha)-protected, C-terminal tetrapeptide alkylamide Z-L-(alphaMe)Val-L-(alphaMe)Phe-L-(alphaMe)Val-L-Iva-NHMe, also reported here, is clearly indicative of the preference of this fully C(alpha)-methylated, short peptide for the 3(10)-helix. As the same terminally blocked sequence is mixed 3(10)/alpha-helical in the L-Abu3 heptapeptide amide but regular 3(10)-helical in the tetrapeptide amide and in the parent heptapeptide amide, these results point to an evident plasticity even of a fully C(alpha)-methylated short peptide.

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“…Peptides with significant Aib content are known to be 3 10 -or ␣/3 10 -helical by NMR, 29,31,32 electron spin resonance (ESR), 33 IR, 34 CD, and vibrational CD data. 27 Homooligomers of Aib are known to be dominantly 3 10 -helical.…”

Section: Introductionmentioning

confidence: 99%

Helix–helix interconversion rates of short ¹³C‐labeled helical peptides as measured by dynamic NMR spectroscopy

et al. 2005

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The rates at which a peptide hexamer and a peptide octamer interconvert between left- and right-handed helical forms in CD2Cl2 solution have been characterized by 13C dynamic NMR (DNMR) spectroscopy. The peptide esters studied are Fmoc-(Aib)n-OtBu (n = 6 and 8), where Fmoc is 9-fluorenylmethyoxycarbonyl and Aib is the strongly helix-forming residue alpha-aminoisobutyric acid. Because the Aib residue is itself achiral, homooligomers of this residue form a 50/50 mixture of enantiomeric 3(10)-helices in solution. It has been demonstrated (R.-P. Hummel, C. Toniolo, and G. Jung, Angewandte Chemie International Edition, 1987, Vol. 26, pp. 1150-1152) that oligomers of Aib interconvert on the millisecond timescale. We have performed lineshape analysis of 13C-NMR spectra collected for our peptides enriched with 13C at a single residue. Rate constants for the octamer range from 6 s(-1) at 196 K to about 56,500 s(-1) at 320 K. At all temperatures, the hexamer interconverts about three times faster than the octamer. Eyring plots of the data reveal experimentally indistinguishable DeltaH++ values for the hexamer and octamer of 37.8 +/- 0.6 and 37.6 +/- 0.4 kJ mol(-1) respectively. The difference in the rates of interconversion is dictated by entropic factors. The hexamer and octamer exhibit negative DeltaS++ values of -29.0(-1) +/- 2.5 and -37.3 +/- 1.7 J K(-1) mol(-1), respectively. A mechanism for the helix-helix interconversion is proposed. and calculated DeltaG++ values are compared to the estimate for a decamer undergoing a helix-helix interconversion.

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Estimating the relative populations of 310-helix and α-helix in Ala-rich peptides: a hydrogen exchange and high field NMR study

Cited by 118 publications

References 51 publications

Early events in the folding of an amphipathic peptide: A multinanosecond molecular dynamics study

Early events in the folding of an amphipathic peptide: A multinanosecond molecular dynamics study

Factors governing 3₁₀‐helix vs α‐helix formation in peptides: Percentage of C^α‐tetrasubstituted α‐amino acid residues and sequence dependence

Helix–helix interconversion rates of short ¹³C‐labeled helical peptides as measured by dynamic NMR spectroscopy

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Estimating the relative populations of 310-helix and α-helix in Ala-rich peptides: a hydrogen exchange and high field NMR study

Cited by 118 publications

References 51 publications

Early events in the folding of an amphipathic peptide: A multinanosecond molecular dynamics study

Early events in the folding of an amphipathic peptide: A multinanosecond molecular dynamics study

Factors governing 310‐helix vs α‐helix formation in peptides: Percentage of Cα‐tetrasubstituted α‐amino acid residues and sequence dependence

Helix–helix interconversion rates of short 13C‐labeled helical peptides as measured by dynamic NMR spectroscopy

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Factors governing 3₁₀‐helix vs α‐helix formation in peptides: Percentage of C^α‐tetrasubstituted α‐amino acid residues and sequence dependence

Helix–helix interconversion rates of short ¹³C‐labeled helical peptides as measured by dynamic NMR spectroscopy