Anaerobic Decomposition of Glutathione in Aqueous Solution

The decomposition of glutathione (GSH) in oxygen free aqueous solution was investigated. The rate of decomposition of GSH was of pseudo first order and depended on pH and the initial concentration. The solution was most stable at pH ranges of 5.0_??_7.5 and its pH-profile showed a curve which was often observed in hydrolysis reactions catalysed by H+ or OH-. The rate constant was increased with the increase of initial concentration of GSH. This suggests the molar inter-relation of GSH. The reducing power of the solution decreased very slightly and only a trace of H2S was formed during storage at pH 4.0_??_7.5. These indicated the stability of the SH residue. From the analysis of decomposition products by paper and gas chromatographies and infra-red spectra, it was concluded that GSH in oxygen free aqueous solution decomposed directly into two portions, pyroglutamic acid (PGA) and cysteinyl-glycine. Glutamic acid was not detected by gas chromatography and the experimental data showed a quantitative relation between decomposed GSH and PGA formed.