Fig. 3. KRpep-2d peptide analogs have dual inhibitory mechanisms. (A) MP-3995 and MP-9903 potently inhibited SOS-mediated nucleotide exchange. The d-Cys5 residue, N- and C-termini, core modifications and thioacetal linker are highlighted in red in the structure. (B) MP-6483, MP-4090, MP-3995, and MP-9903 showed a superior capacity to block the KRAS-RBD PPI compared to KRpep-2d, whereas the non-binder control (MP-4956) had no activity. (C) MP-6483 and MP-1687 blocked the co-immunoprecipitation of b-RAF (left panel) and c-RAF (right panel) with KRASG12D. Alanine mutant peptide library analogs of MP-1687 (Table S1†) demonstrated that KRAS binding affinity correlated well with disruption of the PPI. (D) MP-3995 blocked phospho-ERK signaling in cells expressing either NanoLuc-KRASG12C or NanoLuc-KRASG12C/A59G whereas AMG 510 only inhibited NanoLuc-KRASG12C, non-binders (MP-4956 and MP-9658) had no activity.
