Mathematically combined half-cell reduction potentials of low-molecular-weight thiols as markers of seed ageing

The half-cell reduction potential of the glutathione disulphide (GSSG) / glutathione (GSH) redox couple appears to correlate with cell viability and has been proposed to be a marker of seed viability and ageing. We investigated the relationship between seed viability and the individual half-cell reduction potentials (Eis) of four low-molecular11 weight (LMW) thiols in Lathyrus pratensis seeds subjected to artificial ageing: GSH, cysteine (Cys), cysteinyl-glycine (Cys-Gly) and -glutamyl-cysteine (-Glu-Cys). The standard redox potential of -Glu-Cys was previously unknown and was experimentally determined. The Eis were mathematically combined to define a LMW thiol-disulphide based redox environment (Ethiol-disulphide). Loss of seed viability correlated with a shift in Ethiol-disulphide towards more positive values, with a LD50 value of -0.90 0.093 mV M (mean SD). The mathematical definition of Ethiol-disulphide is envisaged as a step towards the definition of the overall cellular redox environment, which will need to include all known redox-couples