Deep learning-driven rare-event sampling reveals an Ala7/D-Ala8 conformational hinge governing amphiphilic switching in cyclosporine A.

Passive membrane permeability of N-methylated macrocyclic peptides remains poorly understood because high-energy conformational intermediates are rarely sampled by conventional methods. Using the deep learning-driven rare-event sampling framework ES-CRUMPLE, we show that cyclosporine A accesses transient amphiphilic states via a localized conformational hinge at Ala7/D-Ala8, revealing a kinetic design handle that is invisible to population-based analyses.