An L-Type Thioltransferase from Arabidopsis thaliana Leaves

  • Kim, Tae-Soo (Division of Life Sciences. Kangwon National University) ;
  • Cho, Young-Wook (Division of Life Sciences. Kangwon National University) ;
  • Kim, Joon-Chul (Division of Life Sciences. Kangwon National University) ;
  • Jin, Chang-Duck (Division of Life Sciences. Kangwon National University) ;
  • Han, Tae-Jin (Department of Biology, Haliym University) ;
  • Park, Soo-Sun (The National Academy of Sciences) ;
  • Lim, Chang-Jin (Division of Life Sciences. Kangwon National University)
  • Received : 0
  • Accepted : 0
  • Published : 0

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 thioltransferase. 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 L-cysteine. When it was kept for 30 min, it appeared to be very stable up to $70^{\circ}C$. It was activated by $MgCl_2$ and, on the contrary, inhibited by $ZnCl_2$, $MnCl_2$, and $AlCl_3$.

Keywords

Arabidopsis thaliana;Thioltransferase;Glutaredoxin;Dehydroascorbate reductase activity