Investigating the structural changes of myosin under high pressure processing by molecular dynamics simulations.

High-pressure processing (HPP) exerts paradoxical effects on myosin, simultaneously promoting molecular unfolding and supramolecular aggregation, yet the underlying mechanisms remain unresolved at atomic resolution. This study employed all-atom molecular dynamics simulations at gradient pressures (0.1-450 MPa) using complementary monomer and motor domain contact models. The monomer exhibited pressure-induced disruption of intramolecular hydrogen bonds, increased per-residue flexibility (RMSF) and radius of gyration (R g), and expanded the free energy landscape (FEL) toward higher-energy states, demonstrating a "local loosening-global stability" mechanism that exposes buried binding sites without global denaturation. The contact model, in contrast, underwent progressive interfacial compaction, evidenced by restricted R g expansion, SASA reduction, and a broadened free energy landscape spanning diverse metastable sub-basins, yet the nature of this compaction shifted markedly with pressure: at 150 MPa, a specific, hydrophobically stabilized interface with favorable binding affinity was formed, whereas at ≥300 MPa this ordered packing collapsed, giving way to non-specific, electrostatically dominated, volume-constrained aggregation despite persistent structural compaction. These findings suggest that myosin functionality is governed by a shift from site-exposing monomer unfolding at moderate pressures (≤150 MPa) to the progressive collapse of specific interfacial packing and the onset of non-specific, volume-constrained aggregation at extreme pressures (≥300 MPa).