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

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