  A theoretical framework is developed to study the dynamics of protein
folding. The key insight is that the search for the native protein conformation
is influenced by the rate r at which external parameters, such as temperature,
chemical denaturant or pH, are adjusted to induce folding. A theory based on
this insight predicts that (1) proteins with non-funneled energy landscapes can
fold reliably to their native state, (2) reliable folding can occur as an
equilibrium or out-of-equilibrium process, and (3) reliable folding only occurs
when the rate r is below a limiting value, which can be calculated from
measurements of the free energy. We test these predictions against numerical
simulations of model proteins with a single energy scale.
