Computational Study of theStability of the Miniprotein Trp-Cage, the GB1 β-Hairpin,and the AK16 Peptide, under Negative Pressure.

Although hot, cold, and high pressuredenaturation are well characterized,the possibility of negative pressure unfolding has received much lessattention. Proteins under negative pressure, however, are importantin applications such as medical ultrasound, and the survival of biopoloymersin the xylem and adjacent parenchyma cells of vascular plants. Inaddition, negative pressure unfolding is fundamentally important inobtaining a complete understanding of protein stability and naturallycomplements previous studies of high pressure denaturation. We useextensive replica-exchange molecular dynamics (REMD) simulations andthermodynamic analysis to obtain folding/unfolding equilibrium phasediagrams for the miniprotein trp-cage (α-structure, 20-residue),the GB1 β-hairpin (β-structure, 16-residue), and the AK16peptide (α-helix, 16-residue). Although the trp-cage is destabilizedby negative pressure, the GB1 β-hairpin and AK16 peptide arestabilized by this condition. [ABSTRACT FROM AUTHOR]