Protocol for reconstituting peptides/peptidomimetics from DMSO to aqueous buffers for circular dichroism analyses

Circular dichroism (CD) spectrometry is a rapid technique for detecting protein secondary structure, particularly helicity. DMSO is used to ensure optimal solubility of peptides/peptidomimetics; however, its background absorbance hinders effective CD analysis. Here, we present a protocol for reconstituting peptides/peptidomimetics from DMSO to aqueous buffers for CD analyses. We describe steps for identifying chemicals that induce DMSO evaporation, extracting peptides/peptidomimetics from DMSO, and CD spectrometer setup and analysis. We then detail procedures for secondary structure analyses of reconstituted peptides/peptidomimetics. For complete details on the use and execution of this protocol, please refer to Gao et al. (2023).¹