every mole of oxidized glutathione (GSSG), one mole of NADPH is required to
reduce GSSG to GSH. The enzyme forms a FAD bound homodimer. The
glutathione reductase is conserved between all kingdoms. In bacteria, yeasts, and
animals, one glutathione reductase gene is found; however, in plant genomes, two
GR genes are encoded. Drosophila and Trypanosomes do not have any GR at all.
In these organisms, glutathione reduction is performed by either the thioredoxin or
the trypanothione system, respectively.
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