Peptide models for β‐turns.

Crisma, Marco; Fasman, G. D.; Balaram, Hemalatha; Balaram, Padmanabhan

doi:10.1111/j.1399-3011.1984.tb02739.x

Cited by 77 publications

(19 citation statements)

References 31 publications

(2 reference statements)

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“…These observations confirm that the signals at ∼ 198 and 230 nm are independent. It is also suggested that the band at 230 nm could correspond to a β‐turn conformation of the VPGF segment, as the presence of a PG dipeptide motif is commonly responsible for the formation of a turn and that a weak negative band between 220 and 230 nm is characteristic of a n → π* electronic transition for a β‐turn …”

Section: Resultsmentioning

confidence: 99%

Electronic circular dichroism and nuclear magnetic resonance studies of peptides derived from the FKBP52‐interacting β‐turn of the hERα ligand‐binding domain

et al. 2019

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When located at the surface of proteins, turns containing a Pro‐Gly (PG) motif are often involved in protein/protein interactions and may participate in intracellular signaling cascades. As such, conformationally constrained short protein‐derived turn peptides offer promising perspectives for the development of drug candidates in the context of interfering with protein/protein interactions. From X‐ray crystal structures of the human estrogen receptor α ligand‐binding domain (hERα‐LBD), we have identified a short peptide motif (residues 363‐367, sequence: RVPGF) that adopts a type II β‐turn and which is a substrate of the FK1 peptidyl‐prolyl cis‐trans isomerase (PPIase or rotamase) catalytic site of the immunophilin FKBP52, when synthesized independently from the protein. Using ECD and NMR spectroscopy in combination with molecular dynamics simulations, we have embarked on a conformational study of peptides derived from this sequence, and we have explored the effects resulting from N‐ and C‐termini chemical modifications, cyclization, as well as from the replacement of both the proline and its preceding residue by various natural and non‐natural amino acids. All peptides are found to explore several conformational states in aqueous solution, differing by the conformation of the peptide bond preceding the proline residue of the central VPG segment. Trans isomers are characterized by a conformational equilibrium between a type II β‐turn around PG and an extended conformation, while cis isomers adopt a type VIb β‐turn centered on the Xaa‐Pro segment. We show here how limited chemical modifications can deeply influence the turn conformation of this FKBP52‐interacting peptide.

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Section: Resultsmentioning

confidence: 99%

Electronic circular dichroism and nuclear magnetic resonance studies of peptides derived from the FKBP52‐interacting β‐turn of the hERα ligand‐binding domain

et al. 2019

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“…The spectrum in TFE (solid line in panel A) shows a single minimum at ∼ 225 nm. The MeOH spectrum (solid line in panel B) shows a minimum ∼210 nm, a shoulder at 225 nm, a cross over at 205 nm and a positive band at 197 nm suggests that the peptide folds into β‐turn conformation . The spectrum in HFIP (solid line in panel C) shows a broad minimum at ∼ 225 nm and a sharper negative band at 197 nm.…”

Section: Resultsmentioning

confidence: 97%

Self‐assembly of a peptide with a tandem repeat of the Aβ16‐22 sequence linked by a β turn‐promoting dipeptide sequence

2015

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Amyloid deposits have been found to be abundant in patients with Alzheimer's disease due to fibril formation by the Aβ peptides. Peptide Aβ16-22, comprising of the seven-residue segment KLVFFAE, spanning residues 16-22 of the full length Aβ42 peptide, aggregates to form fibrils or other nanostructures in isolation, depending on the conditions of dissolution and incubation. In this study, we have examined the self-assembly of PAβ, a tandem repeat peptide of the Aβ16-22 sequence, joined by a β-turn-inducing sequence Asn-Gly. To study the effect of various solvents on the self-association, hexafluoroisopropanol (HFIP), trifluoroethanol (TFE) and methanol were used. The peptide was also incubated in fibril-promoting conditions of 20% fluorinated alcohol-water mixtures which form dynamical solvent clusters, as well as in 20% MeOH-water mixture which does not form solvent clusters. Secondary structural studies suggest the presence of β-structures. Electron microscopic images indicate that fibril formation occurs in a time-dependent manner, under different conditions of solvent composition. Thioflavin-T fluorescence studies confirm the presence of amyloid fibrils in the aggregates. Although the insertion of the Asn-Gly sequence has not facilitated the formation of an ideal Type I' rigid turn, the intramolecular interactions aid the formation of a flexible β-turn conformation, with twisted β-sheets. Interactions between the intermolecular β-sheets result in the formation of amyloid fibrils. Organic solvents appear to play an important role in modulating self-assembly of peptide PAβ during fibril formation. Studies on β-hairpin engineered amyloidogenic peptides could lead to knowledge about suitable conditions for generating a diverse range of polymorphic structures.

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“…Further information on the change of supramolecular arrangements of IQSPHFF was obtained from the FTIR studies. The literature reports that the most informative frequency ranges are as follows (i) 3200–3400 cm −1 , corresponding to the N—H stretching vibrations of the peptide and N‐protecting urethane groups, and (ii) 1800–1600 cm −1 , corresponding to the CO stretching vibrations of the peptide . Peaks at around 1685 cm −1 can be assigned to the amide I band, and those peak at about 1454 cm −1 are associated with the amide II band .…”

Section: Resultsmentioning

confidence: 99%

A novel self‐assembling peptide with UV‐responsive properties

et al. 2013

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A novel heptapeptide comprising Ile-Gln-Ser-Pro-His-Phe-Phe (IQSPHFF) identified and found to undergo self-assembly into microparticles in solution. To understand the effects of ultraviolet (UV) irradiation on the self-assembly process, IQSPHFF solutions were exposed to the UV light of 365 nm at room temperature. This exposure was found to have a profound effect on the morphology of the self-assembled aggregates, converting the microparticles to nanorod shapes. Circular dichroism and FTIR studies indicated distinct structural differences in the arrangements of the peptide moieties before and after UV irradiation. However, Mass spectrum analysis and high performance liquid chromatography of the peptide molecules before and after UV irradiation demonstrated that the chemical structure of IQSPHFF was not changed. UV-visible spectroscopy and fluorescence spectroscopy studies showed that the absorption peak both increased after UV irradiation. Overall, our data show that the heptapeptide with UV-responsive properties.

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Peptide models for β‐turns.

Cited by 77 publications

References 31 publications

Electronic circular dichroism and nuclear magnetic resonance studies of peptides derived from the FKBP52‐interacting β‐turn of the hERα ligand‐binding domain

Electronic circular dichroism and nuclear magnetic resonance studies of peptides derived from the FKBP52‐interacting β‐turn of the hERα ligand‐binding domain

Self‐assembly of a peptide with a tandem repeat of the Aβ16‐22 sequence linked by a β turn‐promoting dipeptide sequence

A novel self‐assembling peptide with UV‐responsive properties

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