Effect of hydrophilic amino acid substitutions on the solubility and secondary structure of βA (1-42)

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Abstract

Modified sequences of the amyloid peptide βA (1-42) and its shorter Phe-sulfonic acid derivatives with enhanced solubility in aqueous solutions were synthesized, and the conformational consequences were studied by comparative circular dichroism and Fourier transform infrared spectroscopy. Measurements were performed in trifluoroethanol/ water mixtures and aqueous octyl-glucoside solutions. Replacement of the hydrophobic amino acids by less hydrophobic and hydrophilic residues resulted in a predominantly random conformation of the modified amyloid peptides in water, while βA (1-42) exhibited 55% β-sheet structure. In the helix-promoting solvent trifluoroethanol the completely dissolved peptides are present mostly in an α-helical conformation. In octyl glucoside solution - at and above the critical micelle concentration - βA (1-42) has higher β-sheet content (82%), contrary to the more hydrophilic modified peptides which retain a predominant random conformation irrespective of the absence or presence of the micelles. Our data suggest that the amide groups of the backbone and/or the polar side-chain functions of βA (1-42) interact with the glucose surface of micelles possibly mainly by H-bonds creating a β-sheet forming core which then facilitates intersheet stacking. The modified peptides do not bind to the surface of micelles or their binding has no β-ordering effect on the peptide chains.

Original languageEnglish
Pages (from-to)185-192
Number of pages8
JournalBiospectroscopy
Volume2
Issue number3
Publication statusPublished - 1996

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Amino Acid Substitution
Solubility
Peptides
Amino acids
Micelles
Substitution reactions
Amino Acids
Trifluoroethanol
Conformations
Amyloid
Sulfonic Acids
Water
Critical micelle concentration
Dichroism
Fourier Transform Infrared Spectroscopy
Circular Dichroism
Amides
Fourier transform infrared spectroscopy
Glucose
Derivatives

ASJC Scopus subject areas

  • Biochemistry, Genetics and Molecular Biology(all)

Cite this

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title = "Effect of hydrophilic amino acid substitutions on the solubility and secondary structure of βA (1-42)",
abstract = "Modified sequences of the amyloid peptide βA (1-42) and its shorter Phe-sulfonic acid derivatives with enhanced solubility in aqueous solutions were synthesized, and the conformational consequences were studied by comparative circular dichroism and Fourier transform infrared spectroscopy. Measurements were performed in trifluoroethanol/ water mixtures and aqueous octyl-glucoside solutions. Replacement of the hydrophobic amino acids by less hydrophobic and hydrophilic residues resulted in a predominantly random conformation of the modified amyloid peptides in water, while βA (1-42) exhibited 55{\%} β-sheet structure. In the helix-promoting solvent trifluoroethanol the completely dissolved peptides are present mostly in an α-helical conformation. In octyl glucoside solution - at and above the critical micelle concentration - βA (1-42) has higher β-sheet content (82{\%}), contrary to the more hydrophilic modified peptides which retain a predominant random conformation irrespective of the absence or presence of the micelles. Our data suggest that the amide groups of the backbone and/or the polar side-chain functions of βA (1-42) interact with the glucose surface of micelles possibly mainly by H-bonds creating a β-sheet forming core which then facilitates intersheet stacking. The modified peptides do not bind to the surface of micelles or their binding has no β-ordering effect on the peptide chains.",
author = "I. Laczk{\'o} and K. So{\'o}s and Varga, {J{\'o}zsef L.} and E. Vass and M. Holl{\'o}si and B. Penke",
year = "1996",
language = "English",
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journal = "Biopolymers",
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TY - JOUR

T1 - Effect of hydrophilic amino acid substitutions on the solubility and secondary structure of βA (1-42)

AU - Laczkó, I.

AU - Soós, K.

AU - Varga, József L.

AU - Vass, E.

AU - Hollósi, M.

AU - Penke, B.

PY - 1996

Y1 - 1996

N2 - Modified sequences of the amyloid peptide βA (1-42) and its shorter Phe-sulfonic acid derivatives with enhanced solubility in aqueous solutions were synthesized, and the conformational consequences were studied by comparative circular dichroism and Fourier transform infrared spectroscopy. Measurements were performed in trifluoroethanol/ water mixtures and aqueous octyl-glucoside solutions. Replacement of the hydrophobic amino acids by less hydrophobic and hydrophilic residues resulted in a predominantly random conformation of the modified amyloid peptides in water, while βA (1-42) exhibited 55% β-sheet structure. In the helix-promoting solvent trifluoroethanol the completely dissolved peptides are present mostly in an α-helical conformation. In octyl glucoside solution - at and above the critical micelle concentration - βA (1-42) has higher β-sheet content (82%), contrary to the more hydrophilic modified peptides which retain a predominant random conformation irrespective of the absence or presence of the micelles. Our data suggest that the amide groups of the backbone and/or the polar side-chain functions of βA (1-42) interact with the glucose surface of micelles possibly mainly by H-bonds creating a β-sheet forming core which then facilitates intersheet stacking. The modified peptides do not bind to the surface of micelles or their binding has no β-ordering effect on the peptide chains.

AB - Modified sequences of the amyloid peptide βA (1-42) and its shorter Phe-sulfonic acid derivatives with enhanced solubility in aqueous solutions were synthesized, and the conformational consequences were studied by comparative circular dichroism and Fourier transform infrared spectroscopy. Measurements were performed in trifluoroethanol/ water mixtures and aqueous octyl-glucoside solutions. Replacement of the hydrophobic amino acids by less hydrophobic and hydrophilic residues resulted in a predominantly random conformation of the modified amyloid peptides in water, while βA (1-42) exhibited 55% β-sheet structure. In the helix-promoting solvent trifluoroethanol the completely dissolved peptides are present mostly in an α-helical conformation. In octyl glucoside solution - at and above the critical micelle concentration - βA (1-42) has higher β-sheet content (82%), contrary to the more hydrophilic modified peptides which retain a predominant random conformation irrespective of the absence or presence of the micelles. Our data suggest that the amide groups of the backbone and/or the polar side-chain functions of βA (1-42) interact with the glucose surface of micelles possibly mainly by H-bonds creating a β-sheet forming core which then facilitates intersheet stacking. The modified peptides do not bind to the surface of micelles or their binding has no β-ordering effect on the peptide chains.

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