A thermodynamic model of regulation: modulation of redox equilibria in camphor monoxygenase.

Regulation of biological phenomena occurs in all types of systems, being manifested in many different reaction types, from allosteric behavior in proteins, through modulation in energy and information transfer, to the control of growth and differentiation in cells, organelles, and organisms. In this communication, a modulation in oxidation/reduction potential via ligation of substrate and protein components in the camphor 5-exo-monoxygenase system is described in terms of a four-state system using as fundamental parameters the transition free energies between equilibrium states. This approach provides a concise description of the data and is useful for describing many aspects of regulatory phenomena.