The "presodium" hydrogen evolution at the dropping mercury electrode catalysed by simple cysteine peptides

"Presodium" catalytic currents at dropping mercury electrode of cysteine, c ysteinylglycine, gamma -glutamylcysteine and reduced glutathione were syste matically studied in weakly alkaline solutions. They consist in shifts to p ositive potentials of current due to reduction of the blank solution, and, under some conditions, also in formation of "catalytic prewaves". The two c ases have been qualitatively interpreted as based on a suggested common mec hanism, differing by the occurrence of weak catalyst adsorption in the prew ave case. The catalytic activity depends on the catalyst itself (concentrat ion, structure, conformation at the electrode, partial protonation/ionisati on, partial hydrophobic/hydrophilic character) as well as on the solution ( pH, ionic strength, nature and concentration of components).