Figure 5.

(A) The three critical residues (F3, D-Trp⁷, and Cba¹⁰) responsible for the interaction of the peptide with Mdm2 project into a hydrophobic groove on the surface of Mdm2. 2Fo-Fc map for ATSP-7041 variant with a W⁷ to d-Trp substitution (MP-594) peptide is shown in blue and the 2Fo-Fc map for Mdm2 is shown in green (1.5σ). (B) Surface representation of Human Mdm2 (6–125) in complex with MP-594. The 2Fo-Fc electron density map for MP-594 is shown in blue mesh (1.5σ). (C) Alignment of MP-594 (magenta) with the M06 stapled peptide (chain C from PDB ID: 4UMN, yellow) (D) and the SAH-8 stapled peptide (chain B from PDB ID: 3V3B, cyan), both respectively in complex with Mdm2, highlighting the translation (blue arrows) of MP-594 across the peptide binding groove. (E) Overlay of MP-594 and M06, demonstrating that the d-Trp⁷ sidechain of MP-594 occupies the same volume of space as the Trp⁷ in M06 without perturbing the spatial positions of the other critical side chains in relation to each other or the overall α-helical fold of the constrained peptide. Only a global shift in register of the whole peptide occurs to maintain these critical interactions in their optimal positions with Mdm2. (F) Alignment of MP-594 (magenta) with the linear pMI N8A peptide (chain B from PDB ID: 3LNZ, blue), both in complex with Mdm2, where gross differences can be observed between both molecules in terms of displacement along and across the Mdm2 binding pocket (blue arrows).