Currently, the investigation of protein refolding processes involves several time-consuming steps that require large amout of protein. In that context, it has been reported that 2-methyl-2,4-pentanediol (MPD) is able to modulate the denaturing properties of sodium dodecyl sulfate (SDS) and to induce the refolding of proteins. Nonethless and even though this cosolvent effect was previously observed on the refolding of several proteins (including the lysozyme, the carbonic anhydrase, and PagP), little is known about the mechanism by which the MPD can turn the unfolding properties of SDS. The general objective of this thesis was therefore to go deeper in the understanding of the related mechanisms. In that context, a 4-steps strategy was developed: (i) the protcol was extended to the trimeric membrane protein Omp2a in order to demonstrate the transferability of the method to a multimeric protein and determine the optimal detergent/cosolvant ratio. (ii) The combination of experimental (biophysic spectroscopies) and theoretical (molecular dynamics) outputs gives us the opportunity to describe the SDS-induced unfolding states of model peptides. (iii) Then, the key role of MPD to induce the SDS micelle dissociation was unveiled by dynamic light scattering and molecular dynamics simulations. (iv) Finally, the refolding of model peptides was investigated in the presence of the detergent and the cosolvent.