Thermal and dielectric fingerprints of self-assembling elastin peptides derived from exon30

Cirimat, Physique Des Polymères, Université Paul Sabatier, 31062 Toulouse, France ,J Dandurand,A Pepe,C Lacabanne,B Bochicchio,V Samouillan,E Dantras,

doi:10.3934/biophy.2021018

Cirimat, Physique Des Polymères, Université Paul Sabatier, 31062 Toulouse, France , J Dandurand + Show 6 more

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https://doi.org/10.3934/biophy.2021018

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Abstract

Three elastin peptides derived from a peculiar elastin sequence (exon 30) were investigated by Infra-red spectroscopy (IRTF), differential scanning calorimetry (DSC) and dielectric spectroscopy (DDS) to clarify the relationship between structural organization and physical properties of these peptides in the solid state. If a great majority of elastin derived peptides form organized structures, only few are able to coacervate, and only one, that is encoded by Exon 30, gives rise to an irreversible precipitation into amyloid fibers. The peptides studied in this work are constituted by 17, 18 or 22 amino acids whose sequences are contained in the longer exon 30. They all contain the XGGZG sequence (where X, Z = V, L) previously suspected to be responsible for amyloid formation in elastin peptides. Two of them gave rise to amyloid fibers while the other one was able to coacervate. In this work we attempted to correlate vibrational, thermal and dielectric behavior of these peptides in the solid state with the propensity to lead to reversible or irreversible aggregation in vivo.

Highlights

One of the usual properties of tropoelastin is its ability to coacervate, what constitutes the first step of fibrillogenesis of mature elastin
Some polypeptides encoded by Exon 30 (EX30) located in the C-terminal region of the human tropoelastin gene exhibit an ultrastructural organization different from typical fibrils of elastin, and give rise to amyloid fibers [8,9,10,11]
The FTIR spectra of these peptides are typical of polypeptides and proteins, evidencing amide I (C=O stretching), amide II (C-N stretching and N-H bending), and amide III (N-H in plane deformation) bands

Summary

Introduction

One of the usual properties of tropoelastin is its ability to coacervate, what constitutes the first step of fibrillogenesis of mature elastin. Coacervation is a reversible self-assembling [1] which promotes the formation of folded conformations including peculiarly β turn conformations [2] This property depends on several parameters, such as the amino acid sequence, temperature, protein concentration, ionic strength and pH [3]. Some polypeptides encoded by Exon 30 (EX30) located in the C-terminal region of the human tropoelastin gene exhibit an ultrastructural organization different from typical fibrils of elastin, and give rise to amyloid fibers [8,9,10,11]. These fibers are frequently associated with neuro-degenerative diseases [12], Alzheimer’s disease and diabetes [13]. The formation of amyloid fibrils, induced by changes in environment, is an irreversible process that leads to antiparallel alignment of cross β structures

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