Alpha-synuclein (AS) is a natively unfolded protein whose structure is extremely sensitive to its environment. The hallmark of Parkinson’s disease (PD) is aggregation and deposition of AS in inclusion bodies. Formation of misfolded AS monomers which are partially folded is the first and critical stage in fibrillation of AS and is a good target for designing therapeutic strategies. Characterization the biochemical properties of partially folded intermediates induced by fibrillization and anti- fibrillization agents will help to design drugs as new inhibitors of AS misfolding and aggregation. Nanopore analysis is an emerging technique for studying the molecular mechanism of protein misfolding. This technique was used to characterize the conformational change of AS in the presence of two groups of chemicals; anti-parkinsonian small molecules (dopamine and nicotine) and Parkinson’s developing toxin (Cu(II) and methamphetamine). Other biophysical techniques such as NMR spectroscopy and isothermal titration calorimentry (ITC) were able to confirm the nanopore analysis results and also to study other biophysical properties of the partially folded intermediates such as the binding constant of the interaction and the secondary structure content. The results from nanopore analysis showed that both groups of ligands shifted the blockade current peak of AS (centered at -86 pA) to lower blockade currents but in a different manner. Anti-parkinsonian drugs shifted the blockade current of AS to intermediate peaks between -40 to -80 pA but Parkinson developing toxins shifted the peak to a lower blockade current centered at -25 pA which suggests a more compact conformation. Thus nanopore analysis distinguished the different conformation induced by different ligands. Furthermore nanopore analysis with AS fragments showed that these ligands bind to different regions of AS. NMR spectroscopy of AS in the presence of dopamine and nicotine isomers was in agreement with the nanopore analysis and showed conformational changes of AS in a concentration dependent manner. CD spectroscopy results showed that the secondary structure of AS alone and in the presence of ligands was mostly random coil and suggests a loop formation model for the interaction of ligands with AS. The results of this thesis showed the application of nanopore analysis as a real-time and label-free technique to screen a library of ligands for designing misfolding inhibitors for PD treatment. The result of a synergic experiment with nicotine and caffeine showed that combination of these anti-parkinsonian small molecules would be a promising new drug for treatment of PD.

Les poly(triazole amide)s sont une classe de polymères à séquences définies synthétisés par une approche « AB+CD » itérative, chimiosélective et supportée. Cette stratégie permet de contrôler parfaitement la séquence des monomères, puisque les unités constitutives sont ajoutées une à une. De plus, la chimiosélectivité des réactions de couplage permet de s’affranchir d’étapes de déprotection. En outre, l’utilisation d’un support solide minimise également le temps d’expérimentation et facilite les étapes de lavage, réduisant donc le temps total de synthèse. Cette voie de synthèse a été utilisée pour la préparation de différents types de polymères fonctionnels. Premièrement, plusieurs oligomères comme des structures composées de chaînes alkyles ou PEG ont été préparées, contenant des séquences de monomères non naturels qui forment un code binaire. Ces produits ont été analysés grâce à deux techniques de séquençage : la spectrométrie de masse en tandem et l’analyse de chaînes uniques par les nanopores. Une synthèse sans cuivre de ce type d’oligomères a également été considérée. Enfin, une nouvelle classe d’acides xénonucléiques (XNAs), les peptide triazole nucleic acids (PTzNAs), a été synthétisée et étudiée. En particulier, les propriétés d’hybridation de ces polymères contenant des séquences génétiques ont été examinées. / Poly(triazole amide)s are a class of sequence-defined polymers synthesized via a chemoselective iterative “AB+CD” approach on a solid support. This strategy allows to perfectly control the sequence of monomers, since the building blocks are added one by one. Moreover, the chemoselectivity of the coupling reactions enables to avoid the use of deprotection steps and to save time. In addition, the use of a solid support also minimizes the experiment time and facilitates the cleaning steps, thus reducing the total synthesis time. This synthesis pathway was used for the synthesis of different types of functional polymers. First of all, several oligomers such as structures based on alkyl or PEG chains were prepared, containing sequences of non-natural monomers that form a binary code. Those products were analyzed with two sequencing techniques: tandem mass spectrometry and nanopore single-chain analysis. A copper-free synthesis of this type of oligomers was also considered. Then, a new class of xeno nucleic acids (XNAs), peptide triazole nucleic acids (PTzNAs) was synthesized and studied. In particular, the hybridization properties of those natural sequence-containing polymers were investigated.