(NH4)2SO4
less effective than Na2SO4
DTT
DTT can replace glutathione as reductant, 5 mM DTT increases activity 40fold
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chilling at 12°C induces oxidative stress by formation of H2O2 which increases oxidized glutathione concentration in mesophyll cells and bundle-sheath, increases enzyme activity in bundle-sheath cells, and induces enzyme expression in mesophyll cells
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feeding of O-acetylserine leads to increased accumulation of sulfite and thiosulfate in wild-type plants
sulfate
optimal concentration between 350 and 500 mM