TDP-43 is a protein that regulates many aspects of RNA processing. In an abnormal phosphorylated state TDP-43 has been linked to the onset of amyotrophic lateral sclerosis. Cyclophilin A (PPIA) is involved in several cellular processes: it is an enzyme accelerating protein folding and also it is a molecular chaperone protecting against oxidative stress and protein misfolding. PPIA is an interacting partner of TDP-43: lack of this interaction induces TDP-43 mislocalization and aggregation, leading to neurodegeneration.We want to elucidate whether PPIA acts as a chaperone, sequestrating TDP-43 in a one to one complex, or it acts as a foldase, realising the TDP-43 substrate after the folding rearrangement. To address this issue we synthetized three different TDP-43 peptides, belonging to the region that regulates aggregation and inter-protein bonds. We plan to observe the interaction of the peptides with PPIA and how their interplay modifies the kinetics of peptides aggregation.