Cystine andGlutathione
Glutathione (GSH) is a tripeptide composed of
g-glutamate, cysteine and glycine.
The
sulfhydryl side chains of the cysteine residues of two glutathione molecules
form a disulfide bond (GSSG) during the course of
being oxidized in reactions
with various oxides and peroxides in cells. Reduction
of GSSG to two moles of
GSH is the function of glutathione reductase, an
enzyme that requires coupled
oxidation of NADPH.