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.
D'Auria
Gabriella
G
Department of Chemistry, University of Naples "Federico II", 80126 Naples, Italy. gabriella.dauria@unina.it
Vacatello
Manuela
M
Falcigno
Lucia
L
Paduano
Luigi
L
Mangiapia
Gaetano
G
Calvanese
Luisa
L
Gambaretto
Roberta
R
Dettin
Monica
M
Paolillo
Livio
L
D002942:Circular Dichroism; D009682:Magnetic Resonance Spectroscopy; D010455:Peptides / Q000737:chemistry*; D017433:Protein Structure, Secondary
D010455:Peptides