A STRESS-ASSOCIATED CITRUS PROTEIN IS A DISTINCT PLANT PHOSPHOLIPID HYDROPEROXIDE GLUTATHIONE-PEROXIDASE

A protein whose level is markedly increased upon exposure of cultured citrus cells and whole plants to NaCl, was shown to specifically catalyze the reduction of phosphatidylcholine hydroperoxide in the presence of glutathione. This enzymatic activity was shown to be independent of a similar activity exhibited by glutathione S-transferase in plants. This finding corroborates the significant homology (52%) accounted between the deduced amino acid sequence of the gene encoding for this protein and that of mammalian phospholipid hydroperoxide glutathione peroxidases. While the mammalian enzyme is known and well investigated, this study establishes the presence of this key protein also in plants.