Maintains high levels of reduced glutathione in the cytosol. 2 glutathione + NADP(+) = glutathione disulfide + H(+) + NADPH Binds 1 FAD per subunit. kcat is 188.3 sec(-1) with GSSG as substrate (at 25 degrees Celsius and pH 6.9). Optimum pH is 6.8. Inactive at 80 degrees Celsius. Homodimer. Expressed during the parasite blood stage, including in schizonts (at protein level) (PubMed:8631352). Expression is weak in ring, early trophozoite and increases in the late trophozoite and early schizont stage (PubMed:8774709). There are 2 isoforms resulting from alternative translation initiation. The displayed sequence is likely to represent the shorter isoform. The active site is a redox-active disulfide bond. Belongs to the class-I pyridine nucleotide-disulfide oxidoreductase family.