Glutaredoxin(thioltransferase) has been identified and purified to homogeneity from spinach leaves. Its cytosolic localization was demonstrated by chromatographic and immunological analysis of extracts from isolated spinach chloroplasts and mitochondria, respectively. Spinach glutaredoxin shows a significant crossreactivity with antibodies raised against E. coli glutaredoxin and possesses a specific thioltransferase activity comparable to that of the E. coli protein. Minor thioltransferase activities (less than 10% of total leaf activity) have been observed in spinach chloroplasts which are probably due to the presence of trypsin inhibitor and thioredoxins (TRf and TRm).
