From phage display and venoms to protease-resistant peptides: design of bbb-shuttles and peptides targeting egf

• Autores: Cristina Díaz Perlas
• Directores de la Tesis: Ernest Giralt Lledó (dir. tes.), Meritxell Teixidó Turá (dir. tes.)
• Lectura: En la Universitat de Barcelona ( España ) en 2018
• Idioma: español
• Tribunal Calificador de la Tesis: David Andreu Martínez (presid.), Judit Tulla Puche (secret.), Luca Domenico D'Andre (voc.)
• Programa de doctorado: Programa de Doctorado en Química Orgánica por la Universidad de Barcelona
• Materias:
  • Química
    • Bioquímica
      • Péptidos
    • Química macromolecular
      • Polipéptidos y proteínas
• Enlaces
  • Tesis en acceso abierto en: TDX
• Resumen

  • In this thesis we have designed, synthesised and evaluated peptides as ligands for the epidermal growth factor (EGF) and as BBB-shuttles able to transport therapeutics into the brain. EGF is overexpressed in several cancers and the proliferation of these cells could be reduced by inhibiting EGF. Mirror image phage display methodology was applied to this protein to obtain protease-resistant ligands. In this way, the protein was synthesised, using D-amino acids, by a combination of solid-phase peptide synthesis and native chemical ligation. Then, the panning of two phage display peptide libraries against the immobilised protein gave peptide sequences as ligand candidates. Finally, the synthesis of these ligands, with D-amino acids, and their evaluation produced three peptide sequences with high binding affinities for EGF and stabilities in human serum. Most potential drugs for the treatment of central nervous system disorders do not cross the blood-brain barrier (BBB). Much effort has been devoted to the discovery of new BBB-shuttles, with the capacity to transport therapeutics across the BBB. We have applied phage display to an in vitro BBB cellular model to discover peptide sequences as new BBB-shuttles. After the panning, the best sequence was synthesised and was able to cross the BBB and improve the uptake of a model protein. Furthermore, the branched dimerisation of a known BBB-shuttle was explored. After its synthesis, it was conjugated to a model protein and its BBB transport evaluated. The results suggest that the mild improvement in permeability may not compensate the increased synthetic effort. Finally, new BBB-shuttles have been designed and synthesised from a peptide found in a scorpion venom that is able to reach the brain. Their BBB properties have been evaluated and their permeability values are similar compared to the best BBB-shuttles.