Low Force Unfolding of a Single-Domain Protein by Parallel Pathways

Deviations from linearity in the dependence of logarithm protein unfolding rates, log ku(f), as a function mechanical force, f, measurable single molecule experiments, can arise for many reasons. In particular, upward curvature ku(f) f implies that underlying energy landscape must be multidimensional with possibility ensues by parallel pathways. Here, simulations using SOP-SC model wild type β-sandwich and several mutants, immunoglobulin folds, show kinetics. There are substantial changes structures transition state ensembles force is increased, signaling switch Our results, when combined previous theoretical experimental studies, structurally unrelated domain proteins determined (or ku[C] where [C] denaturant concentration).