LS2P provides information about structural propensities in Intrinsically Disordered Proteins (IDPs). In addition to identifying scarcely populated helical and extended regions, the method pinpoints short stretches triggering β-turn formation or promoting α-helices. LS2P performs statistical analyses from a database of three-residue fragments extracted from coil regions of high-resolution protein structures. For each residue, conformations are classified into three main regions: (α) right-handed helical conformations, (β) right-handed extended conformations, and (γ) left-handed conformations. The combination of these three regions for each residue defines 27 structural classes for a tripeptide. LS2P computes the propensity of each tripeptide to be observed in each one of these structural classes, taking into account the local sequence context. Values larger than 1.0 for a given structural class indicate that this class is favored for a given tripeptide in the local sequence context, while values below 1.0 indicate the unlikelihood of this class. As input, LS2P requires a FASTA-type sequence (single-letter code for the amino acid residues). It provides two output files: a table (in tsv format) with the propensities of the 27 structural classes for the middle residue of each tripeptide, and a plot (in pdf format) showing propensities for helical and extended conformations, as well as concatenations of propensities (ββα, βαα, ααβ, αββ) enabling the identification of β-turns. Additional explanations about the method can be found in (please cite this publication if you use LS2P in your work) : A. Estaña, A. Barozet, A. Mouhand, M. Vaisset, C. Zanon, P. Fauret, N. Sibille, P. Bernadó, J. Cortés. “Predicting secondary structure propensities in IDPs using simple statistics from three-residue fragments”. Journal of Molecular Biology, 432(19):5447-5459, 2020. https://doi.org/10.1016/j.jmb.2020.07.026 , https://hal.laas.fr/hal-02920302