MECHANICAL CONTROL OF REDOX ENTHALPY

The change in elastic energy which accompanies transfer of an electron to an acceptor site in a protein is formulated. The sign and magnitud e of this energy is found to depend upon the structural geometry to wh ich the site is constrained by the stiffness of the protein. Through t his enthalpy component, conditions which alter protein structure can c ontribute to the control of the oxidation-reduction equilibrium at the site. The difference between the total redox enthalpy and the elastic component is the electrostatic contribution. The formulation is appli ed to the electron acceptor site in the blue cupric protein azurin.