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Self-Organizing Bio-structures

Self-Organizing Bio-structures. NB2-2008 L. Duroux. Lecture 7. Protein-based nanomaterials. 1. Peptide-based nanostructures. A first insight into SA peptides. Concept of peptide SA introduced by Ghadiri et al. (1993)

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Self-Organizing Bio-structures

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  1. Self-Organizing Bio-structures NB2-2008 L. Duroux

  2. Lecture 7 Protein-based nanomaterials

  3. 1. Peptide-based nanostructures

  4. A first insight into SA peptides • Concept of peptide SA introduced by Ghadiri et al. (1993) • Synthetic cyclic polypeptides (alternate L- & D-) self-assemble into Ø8-9nm nanotubes • Function as novel antimicrobial agents, drug delivery systems & nanomaterials

  5. Ghadiri’s cyclic polypeptides (CPP)

  6. Electronic microscopy

  7. pH-dependance of CP SA

  8. CPP forming pores in membranes

  9. Self-Assembling Peptide Nanotubes • cyclic-peptides self-assembled into open tubes • consist of an even number of alternated D / L amino acids • formation of anti-parallel hydrogen bonded network • assembly could be controlled by electrostatic interactions • assembly could be directed toward particular environments (hydrophobic) by selection of amino acids • are functional material (ion channel & antibiotic)

  10. SA based on native 2ndary structural motifs

  11. Protein structural motifs & SA designs Amyloid fibrils Type II polyPro helix

  12. SA Fibers engineering based on coiled-coils Woolfson & Ryadnov, 2006

  13. Amyloid peptides • A generic, universal form of protein/peptide aggregation • Cause of many diseases: Altzheimer’s, Type II diabetes, Prions... • Extended b-sheet SA forming fibrils

  14. Nano-object formed by amyloid peptides Object formed Amyloid fibrils (pancreas type II diabetes) Amyloid fibrils Nanotubes Nanospheres

  15. The role of aromatics in amyloid fibrils formation • Phe dipeptide: the recognition core of Altzheimer’s amyloid fibril • Forms nanotubes • Applications in nano-electronics

  16. SA based on amphiphilicity

  17. Structures of peptides used in SA Boloamphiphile Amphiphile Surfactant-like Phenylalanine dipeptide Reches and Gazit, 2006

  18. Peptide nanotubes Applications Nanotubes with Ca-binding and cell-adhesion  bone-like material Idem, non-conjugated Nanofibers forming hydrogel  matrix for tissue regeneration & engineering

  19. Peptide-Amphiphile and Tissue Engineering SA fibers with CCCCGGGS(PO4)PGD: without Ca2+ (a) and Ca2+ (b)

  20. Aromatic dipeptides

  21. Hydrophobic layers made with dipeptides Görbitz, 2006

  22. Types of nanostructures from various dipeptides

  23. SA of Val-Ala class

  24. SA patterns of the Phe-Phe class Phe-Trp Phe-Gly Phe-Leu Phe-Phe

  25. Formation of nanotubes with Phe-Phe dipeptides

  26. 2. Protein-based SA nanotools

  27. S-layer proteins

  28. What are S-Layer proteins? • S stands for surface: glycoprotein subunits forming outer envelope of Bacteria and Archea • Periodic structures with defined physico-chemical properties (pore size) • Self_assemble into 2D layers to form monomolecular lattices: potential in nanobiotechnologies (scaffolds, patterning matrices)

  29. Applications of S-layers • production of isoporous ultrafiltration membranes • supporting structures for defined immobilization or incorporation of functional molecules (e.g. antigens, antibodies, ligands, enzymes) • matrix for the development of biosensors including solid-phase immunoassays and label-free detection systems • Support and stabilizing matrices for functional lipid membranes, liposomes, and emulsomes • adjuvants for weakly immunogenic antigens and haptens • Matrix for controlled biomineralization and structure for formation of ordered arrays of metal clusters or nanoparticles (molecular electronics and nonlinear optics or catalysts)

  30. S-Layer lattices 100nm Gram+ bacterium

  31. Self-Assembled monomolecular layers

  32. S-layer as template for PSA detection

  33. Assembly of lipids on S-layers • Non-covalent bonding • Electrostatic interactions between corrugated (inner) side of S-layer (carboxy groups) and charges on lipid head groups (zwitterions) • 2-3 contact points between protein and lipid: most lipids free to diffuse laterally: semi-rigid membrane

  34. S-layers as support for lipid membranes

  35. Self-Assembly of a ion-channel in S-layers

  36. Expected applications of S-layer-driven SA of lipid membranes • Life Sciences: • Drug delivery • Diagnostics • Biosensors • Chemistry and material sciences • Bio-mineralization • Non-linear optics • Molecular electronics • Catalysis

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