Sequence‐dependence of secondary structure formation

Altmann, Karl‐Heinz; Flörsheimer, Andreas; Mutter, Manfred

doi:10.1111/j.1399-3011.1986.tb01826.x

Cited by 35 publications

(7 citation statements)

References 30 publications

(5 reference statements)

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“…Weitere Oligopeptide des Typs (Leu‐Ser) n ( II in Tabelle 1)20a sowie von Amyloid‐β‐abgeleitete Sequenzen ( III )2, 6 – alle mit hohem Potenzial zur β‐Faltblatt‐ und Fibrillenbildung – wurden hergestellt. CD‐, IR‐ und EM‐Studien zufolge unterbricht ein eingebautes Schaltelement S die geordneten Strukturen.…”

Section: Synthetisierte Switch‐peptideunclassified

Highly Efficient Suzuki–Miyaura Coupling of Heterocyclic Substrates through Rational Reaction Design

Fleckenstein

Plenio

2008

Chemistry A European J

120

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A dicyclohexyl(2-sulfo-9-(3-(4-sulfophenyl)propyl)-9H-fluoren-9-yl)phosphonium salt was synthesized in 64% overall yield in three steps from simple commercially available starting materials. The highly water-soluble catalyst obtained from the corresponding phosphine and [Na(2)PdCl(4)] enabled the Suzuki coupling of a broad variety of N- and S-heterocyclic substrates. Chloropyridines (-quinolines) and aryl chlorides were coupled with aryl-, pyridine- or indoleboronic acids in quantitative yields in water/n-butanol solvent mixtures in the presence of 0.005-0.05 mol % of Pd catalyst at 100 degrees C, chloropurines were quantitatively Suzuki coupled in the presence of 0.5 mol % of catalyst, and S-heterocyclic aryl chlorides and aryl- or 3-pyridylboronic acids required 0.01-0.05 mol % Pd catalyst for full conversion. The key to the high activity of the Pd-phosphine catalyst is the rational design of the reaction parameters (i.e., the presence of water in the reaction mixture, good solubility of reactants and catalyst in n-butanol/water (3:1), and the electron-rich and sterically demanding nature of the phosphine ligand).

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Section: Synthetisierte Switch‐peptideunclassified

Highly Efficient Suzuki–Miyaura Coupling of Heterocyclic Substrates through Rational Reaction Design

Fleckenstein

Plenio

2008

Chemistry A European J

120

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“…Sequence length is one parameter that has been shown to affect both self‐assembly propensity and the emergent properties of the assembled materials . For example, amphipathic Ac‐(RADA) 4 ‐NH 2 and Ac‐(AKAE) 4 ‐NH 2 peptides undergo favorable self‐assembly into fibrils that entangle to form a hydrogel network .…”

Section: Introductionmentioning

confidence: 99%

Sequence length determinants for self‐assembly of amphipathic β‐sheet peptides

2013

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Amphipathic peptides composed of alternating hydrophobic and hydrophilic amino acids are a privileged class of peptide, which have a high propensity to self-assemble into β-sheet fibrils. The Ac-(FKFE)2-NH2 peptide has been extensively studied and forms putative β-sheet bilayer fibrils in which the hydrophobic Phe side chains are organized to a single face of each constituent sheet; upon bilayer formation, these hydrophobic benzyl groups are sequestered in the hydrophobic core of the resulting fibril. In order for the Phe side chains to be uniformly displayed on one face of Ac-(FKFE)2-NH2 β-sheets, an antiparallel packing orientation in which one amino acid residue is unpaired must be adopted. Based on molecular models, we hypothesized that truncated seven amino acid derivatives of Ac-(FKFE)2-NH2 in which either the N-terminal Phe residue (Ac-KFEFKFE-NH2) or the C-terminal Glu residue (Ac-FKFEFKF-NH2) is eliminated should readily self-assemble into β-sheet bilayers in which all hydrogen bond and hydrophobic/charge interactions are satisfied. We found, however, that these minute changes in peptide sequence have unanticipated and dramatic effects on the self-assembly of each peptide. Ac-FKFEFKF-NH2 self-assembled into fibrils with unique morphology relative to the parent peptide, whereas the Ac-KFEFKFE-NH2 peptide had a strongly reduced propensity to self-assemble, even failing to self-assemble altogether under some conditions. These findings provide significant insight into the effect of sequence length and strand registry as well as hydrophobicity and charge on the self-assembly of simple amphipathic peptides to illuminate the possibility of tuning self-assembly processes and the resulting structures with minute changes to peptide sequence.

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“…[11] Here, we present the synthesis and self-organization behavior of a symmetrically substituted A-B-A-type bioinspired semiconductor, quaterthiophene-peptide hybrid 8 (Scheme 1b), by combining a central quaterthiophene segment (B) with two peptide-poly(ethylene oxide) bioconjugates (A).As outlined in Scheme 1, the oligothiophene segment was substituted on both sides with an amino acid sequence Gly-(Thr-Val) 3 -Gly-aPhe-Gly (Scheme 1, structure 2), with Gly ¼ glycine, Val ¼ valine, Thr ¼ threonine, and aPhe ¼ 4-azidophenyl-alanine. The peptide contains repeats of alternating threonines and valines, which are known to have a high propensity to adopt bsheets in both water [12][13][14] and some organic media. [15] To realize isolated fibrillar nanostructures, the functional segment (peptideblock-quaterthiophene-block-peptide) was laterally shielded by attaching poly(ethylene oxide) blocks (PEO) to the N-termini of both peptide segments, which should prevent lateral interactions and enhance solubility.In order to control the competition of the different intermolecular forces in the peptide and the quaterthiophene segments during synthesis, and the subsequent self-assembly process, the organization tendency of the peptide (Thr-Val) x aggregator domain has been temporarily suppressed.…”

mentioning

confidence: 99%

“…As outlined in Scheme 1, the oligothiophene segment was substituted on both sides with an amino acid sequence Gly-(Thr-Val) 3 -Gly-aPhe-Gly (Scheme 1, structure 2), with Gly ¼ glycine, Val ¼ valine, Thr ¼ threonine, and aPhe ¼ 4-azidophenyl-alanine. The peptide contains repeats of alternating threonines and valines, which are known to have a high propensity to adopt bsheets in both water [12][13][14] and some organic media. [15] To realize isolated fibrillar nanostructures, the functional segment (peptideblock-quaterthiophene-block-peptide) was laterally shielded by attaching poly(ethylene oxide) blocks (PEO) to the N-termini of both peptide segments, which should prevent lateral interactions and enhance solubility.…”

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confidence: 99%

Oligothiophene Versus β‐Sheet Peptide: Synthesis and Self‐Assembly of an Organic Semiconductor‐Peptide Hybrid

et al. 2009

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Investigation of self-organization behavior of organic (semi)-conductors became very important recently, since their physical properties and performance in organic electronic devices strongly depend on ordering effects, on both molecular and nanoscale levels. [1] In this respect, bioinspired functionalization of conjugated systems might greatly enhance the diversity of electronically interesting assemblies, and potentially allow for the rational design of hierarchically ordered nanostructures.[2] Thus, from possible hybrids of conjugated backbones, the combination of oligo-or polythiophenes with biomolecules, such as nucleotides, [3] carbohydrates, [4] or peptides, [5] are interesting. Particularly, the latter appears to be attractive, because interplay between different intermolecular forces in the peptide and oligothiophene segments results in competing self-assembly motifs. Hence, very specific organization properties can be expected. Whereas thiophene-based materials typically form well-organized 2D lamellar superstructures due to van der Waals interactions of alkyl side chains, and stack into the third dimension via p-p interactions, [6] secondary structures of peptides, preferentially bsheets or a-helices, are governed by stronger and directed hydrogen-bond formation.[7] The high tendency of peptides to adopt well-defined secondary-structure motifs has been exploited recently to guide self-organization of a broad range of synthetic polymers.[8] Attention has mainly been devoted to the b-sheet motif, leading to anisotropic fibrillar or fiber-like structures. [9] However, other highly interesting assembly motifs, for example the coiled-coil motif, were exploited, resulting in distinct nanoobjects by the lateral assembly of amphiphilic a-helices. [10] We recently presented the first conjugate between a regioregularly alkylated quaterthiophene and a pentapeptide consisting of a silk-inspired sequence of alanine-glycine repeats, which is known to adopt b-sheet structures.[5a] Unexpected and novel 3D nanostructures were found, suggesting that short peptide sequences may indeed influence the nanoscale structure, and ultimately, properties of organic semiconducting materials.The versatility of this class of hybrid oligo-/polymers is certainly not exploited, considering the diversity of both the conjugated oligo-/polymer platforms and the bioorganic segments. It becomes increasingly evident that such materials will envelop by far more structural and functional space as, for example, common AB-block copolymer systems.[11]Here, we present the synthesis and self-organization behavior of a symmetrically substituted A-B-A-type bioinspired semiconductor, quaterthiophene-peptide hybrid 8 (Scheme 1b), by combining a central quaterthiophene segment (B) with two peptide-poly(ethylene oxide) bioconjugates (A).As outlined in Scheme 1, the oligothiophene segment was substituted on both sides with an amino acid sequence Gly-(ThrVal) 3 -Gly-aPhe-Gly (Scheme 1, structure 2), with Gly ¼ glycine, Val ¼ valine, Thr ¼ threonine, ...

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Sequence‐dependence of secondary structure formation

Cited by 35 publications

References 30 publications

Highly Efficient Suzuki–Miyaura Coupling of Heterocyclic Substrates through Rational Reaction Design

Highly Efficient Suzuki–Miyaura Coupling of Heterocyclic Substrates through Rational Reaction Design

Sequence length determinants for self‐assembly of amphipathic β‐sheet peptides

Oligothiophene Versus β‐Sheet Peptide: Synthesis and Self‐Assembly of an Organic Semiconductor‐Peptide Hybrid

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