An L-Type Thioltransferase from Arabidopsis thaliana Leaves = An L-Type Thioltransferase from Arabidopsis thaliana Leaves

다국어 초록 (Multilingual Abstract)

Thioltransferase, also called glutaredoxin, is a general GSH-disulfide reductase of importance for redox regulation. Previously, the protein thioltransferase, now called S-type thioltransferase, was purified and characterized from Arabidopsis thaliana seed. In the present study, a second thioltransferase, called L-type thioltransferase, was purified to homogeneity from Arabidopsis thaliana leaves. The purification procedures included DEAE-cellulose ion-exchange chromatography, Sephadex G-50 gel filtration, and glutathione-agarose affinity chromatography. The purified enzyme was confirmed to show a unique band on SDS-PAGE and its molecular weight was estimated to be 26.6 kDa, which appeared to be atypical compared with those of most other thioltransferases. It could utilize 2-hydroxyethyl disulfide, S-sulfocysteine, and insulin as substrates, and also contained dehydroascorbate reductase activity. Its optimum pH was 8.5 and its activity was greatly activated by z-cysteine. When it was kept for 30 min, it appeared to be very stable up to 70℃. It was activated by MgCl₂ and, on the contrary, inhibited by ZnCl₂, MnCl₂, and AlCl₃.