Thioltransferase from Arabidopsis thaliana Seed: Purification to Homogeneity and Characterization

Thioltransferase from Arabidopsis thaliana Seed: Purification to Homogeneity and Characterization

Thioltransferase is a general GSH-disulfide reductase of Importance for redox regulation. The protein tbioltransferase has been purified to apparent homogeneity on SDS-PAGE from the Arabidopsis thalina seed. The purification procedures included DEAE-cellulose ion exchange chromatography, Sephadex G-75 gel filtration, Q-Sepharose ion exchange chromatograpby, and DEAE-Sephadex A-25 ion exchange chromatography. The enzyme has a molecular mass of 22 kDa and a pI of 4.8, and it is beatstable. Thc protein bad broad specificities for substrates ranging from low-molecular disulfides (S-sulfocysteine and cystine) to protein disulfides (trypsin and insulin). However, it could not reduce the disulfide linkages of ribonuclease A and bovine serum albumin. It could utilize non-disulfide substrates such as dehydroascorbic acid and alloxan. The protein can reduce the disulfide bond in 2-bydroxyetbyl disulfide with an optimum pH or 8.5. Its activity was greatly activated by monothlol compounds such as reduced glutathione and L-cystelne. Keyword: Arabidopsis thaliana; Glutaredoxin, Thioltransferase