A simple method for the determination of reduction potentials in heme proteins

We describe a simple method for the determination of heme protein reduction potentials. We use the method to determine the reduction potentials for the PAS-A domains of the regulatory heme proteins human NPAS2 (E-m = 115 mV +/- 2 mV, pH 7.0) and human CLOCK (E-m = 111 mV +/- 2 mV, pH 7.0). We suggest that the method can be easily and routinely applied to the determination of reduction potentials across the family of heme proteins. (C) 2014 The Authors. Published by Elsevier B.V. on behalf of the Federation of European Biochemical Societies.