Heterogeneous Physico-Chemical Interactions Following Electrode Reaction: Interaction of Folates with Thiols

Folates do not react chemically with thiols in solution, however, they cause shifts of voltammetric reversible reduction peaks of disulfides towards positive potentials. This is explained as due to the formation of adducts between folates and thiols at the electrode surface. Analogous shifts, but towards negative potentials, were observed with the voltammetric reversible oxidation peak of a reduced form of folic acid after addition of thiols, and were ascribed to the same cause. According to this interpretation the shifts would provide a measure of free enthalpy of the weak interaction between the two partners and the electrode. It is suggested that the observed effect could serve as a simplified model of processes which occur between folates and proteins in the microheterogeneous structure of the living matter.