Keywords: Circular Dichroism, Magnetic Resonance Spectroscopy, Peptides Chemistry, Protein Structure, Secondary, β-Propensity, Amyloidosis, Bio-Membrane, Diffusion, Eak16-Ii Analogs, Pfgnmr, Sans, Self-Assembling, Amyloid Beta Protein, Synthetic Peptide, Amino Acid Sequence, Article, Controlled Study, Hydrophobicity, Priority Journal, Protein Aggregation, Protein Assembly, Protein Conformation, Nuclear Magnetic Resonance Spectroscopy, Protein Secondary Structure, ß-Propensity,
Affiliations: *** IBB - CNR ***
Department of Chemistry, University of Naples "Federico II", 80126 Naples, Italy. gabriella.dauria@unina.it
Institute of Biostructures and Bioimaging, CNR, 80134 Naples, Italy
Consorzio per lo Sviluppo dei Sistemi a Grande Interfase (CSGI), Italy
References: Not available.
Self-assembling properties of ionic-complementary peptides
Self-complementary synthetic peptides, composed by 8 and 16 residues, were analyzed by CD, NMR and small angle neutron scattering (SANS) techniques in order to investigate the relevance of charge and hydrophobic interactions in determining their self-assembling properties. All the sequences are potentially able to form fibrils and membranes as they share, with the prototype EAK16, a strictly alternating arrangement of polar and nonpolar residues. We find that 16-mer peptides show higher self-assembling propensities than the 8-mer analogs and that the aggregation processes are favored by salts and neutral pH. Peptide hydrophobic character appears as the most relevant factor in determining self-assembling. Solution conformational analysis, diffusion and SANS measurements all together show that the sequences with a higher self-assemble propensity are distributed, in mild conditions, between light and heavy forms. For some of the systems, the light form is mostly constituted by monomers in a random conformation, while the heavy one is constituted by beta-aggregates. In our study we also verified that sequences designed to adopt extended conformation, when dissolved in alcohol-water mixtures, can easily fold in helix structures. In that media, the prototype of the series appears distributed between helical monomers and beta-aggregates. It is worth noticing that the structural conversion from helical monomer to beta-aggregates, mimics beta-amyloid peptide aggregation mechanisms. Copyright (C) 2008 European Peptide Society and John Wiley & Sons, Ltd.
Self-assembling properties of ionic-complementary peptides