THIOL-GROUPS IN PROTEINS AS ENDOGENOUS REDUCTANTS TO DETERMINE GLUTATHIONE-PROTEIN MIXED DISULFIDES IN BIOLOGICAL-SYSTEMS

A novel method for glutathione-protein mixed disulphide (GSSP) determi nation, based on the use of protein sulphydryl groups as endogenous re ductant and on the spectrophotometric determination of reduced glutath ione, is described. The procedure is based on the observation that aci d-precipitated proteins from different rat tissues rapidly release GSH from GSSP when brought to neutral pH. The basal GSSP content determin ed in rat liver, heart, lung, testis, spleen and brain corresponded to that reported in the literature and determined by more complex sample preparation or labor-intensive analytical procedures.