 Thus, formula_4 is positive if the unfolded state is less stable (i.e., disfavored) relative to the native state.The most direct way to measure the conformational stability formula_4 of a molecule with two-state folding is to measure its kinetic rate constants formula_1 and formula_2 under the solution conditions of interest.However, since protein folding is typically completed in milliseconds, such measurements can be difficult to perform, usually requiring expensive stopped flow or (more recently) continuous-flow mixers to provoke folding with a high time resolution.