The system VO2+ +oxidized glutathione: a potentiometric and spectroscopic study

The equilibria in the system VO2+ +oxidized glutathione in aqueous solution have been studied in the pH range 2-11 by a combination of pH potentiometry and spectroscopy (EPR, visible absorption and circular dichroism). The results of the various methods are self-consistent and the equilibrium model includes the species MLH4, MLH3, MLH2, MLH, ML, MLH(-1), MLH(-2) and several hydrolysis products (where H4L denotes oxidized glutathione); individual formation constants and spectra are given. Plausible structures for each stoichiometry are discussed.