Kinetics of Reversible Denaturation of Trypsin in Water and Water–Ethanol Mixtures

Abstract

The kinetics of the reversible denaturation of trypsin at pH 1–3 have been measured by following the change in absorption and optical rotation after temperature‐jumps. This structure‐change can be described by an equilibrium between two states of the protein. A kinetic mechanism, involving the binding of two protons to identical sites with differing pK in the two states, can account for the results. The temperature‐dependence of Δ H ° is due to the renaturation step as indicated by the corresponding activation‐energy. Measurements in ethanol–water mixtures suggest that this might be caused by a change of solvation of non‐polar groups with temperature. Reasons for using this denaturation of trypsin as a model‐system for studying the kinetics of structure‐changes in proteins are discussed.