title: Conformational and thermal characterization of a synthetic peptidic fragment inspired from human tropoelastin: Signature of the amyloid fibers.
abstract: OBJECTIVE
  This work deals with the conformational and thermal characterization of a synthetic peptide (S4) released during the proteolysis of human tropoelastin by the matrix metalloproteinase-12 that was shown to form amyloid-like fibres under certain conditions.
  
  
  METHODS
  S4 peptides were synthesized by solid-phase methodology and aggregated in solution at 80°C. Fourier transform-infrared spectroscopy (FT-IR) was used to access the secondary structure. Thermal characterization was performed by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).
  
  
  RESULTS
  The DSC study of the soluble linear peptide S4 in solution in TBS reveals the irreversible aggregation into amyloid fibres. FT-IR, DSC and TGA analyses performed on freeze-dried samples evidence differences between the linear peptide and its associated amyloid-like fibres, both on the conformation and the physical structure. When S4 peptides are aggregated, the prominent conformation scanned by FT-IR is the cross β-structure, corresponding to TGA to an increase of the thermal stability. Moreover, the DSC thermograms of S4 fibres are characteristic of a highly ordered structure, in contrast to the DSC thermograms of S4 linear peptides, characteristic of an amorphous structure. Finally, the DSC analysis of differently hydrated S4 fibres brings to the fore the specific thermal answer of the wet interfaces of the cross β-fibres.
  
  
  CONCLUSIONS
  FT-IR and thermal techniques are well suited to evidence conformational and structural differences between the soluble peptide and its amyloid form.
authors.affiliation: Physique des Polymères, CIRIMAT UMR 5085, Institut Carnot, Université Paul Sabatier, 118, route de Narbonne, 31062 Toulouse cedex, France.
authors.forename: J
authors.initials: J
authors.lastname: Dandurand
authors.affiliation: Physique des Polymères, CIRIMAT UMR 5085, Institut Carnot, Université Paul Sabatier, 118, route de Narbonne, 31062 Toulouse cedex, France. Electronic address: valerie.samouillan@univ-tlse3.fr.
authors.forename: V
authors.initials: V
authors.lastname: Samouillan
authors.affiliation: Physique des Polymères, CIRIMAT UMR 5085, Institut Carnot, Université Paul Sabatier, 118, route de Narbonne, 31062 Toulouse cedex, France.
authors.forename: M H
authors.initials: MH
authors.lastname: Lacoste-Ferre
authors.affiliation: Physique des Polymères, CIRIMAT UMR 5085, Institut Carnot, Université Paul Sabatier, 118, route de Narbonne, 31062 Toulouse cedex, France.
authors.forename: C
authors.initials: C
authors.lastname: Lacabanne
authors.affiliation: Department of Sciences, University of Basilicata, Via Ateneo Lucano, 10, 85100 Potenza, Italy.
authors.lastname: B Bochicchio
authors.affiliation: Department of Sciences, University of Basilicata, Via Ateneo Lucano, 10, 85100 Potenza, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Pepe
mesh_terms: D000595:Amino Acid Sequence; D000682:Amyloid / Q000737:chemistry*; D058227:Amyloidogenic Proteins / Q000138:chemical synthesis / Q000737:chemistry*; D002152:Calorimetry, Differential Scanning; D005612:Freeze Drying; D006358:Hot Temperature; D006801:Humans; D053508:Matrix Metalloproteinase 12 / Q000378:metabolism; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry*; D066329:Protein Aggregates; D011487:Protein Conformation; D011489:Protein Denaturation; D012995:Solubility; D017550:Spectroscopy, Fourier Transform Infrared; D013329:Structure-Activity Relationship; D013818:Thermogravimetry; D014333:Tropoelastin / Q000737:chemistry*; D017155:Wettability
chemical_list: D000682:Amyloid; D058227:Amyloidogenic Proteins; D010446:Peptide Fragments; D066329:Protein Aggregates; D014333:Tropoelastin; C507122:MMP12 protein, human; D053508:Matrix Metalloproteinase 12
keywords: Amyloid fibers; Analyse thermique; Conformation secondaire; Elastin; Fibres amyloïdes; Peptide synthétique; Secondary conformation; Synthetic polypeptide; Thermal analysis; Élastine