Thioltransferase from Arabidopsis thaliana seed: purification to homogeneity and characterization.
Thioltransferase is a general GSH-disulfide reductase of importance for redox regulation. The protein thioltransferase has been purified to apparent homogeneity on SDS-PAGE from the Arabidopsis thaliana seed. The purification procedures included DEAE-cellulose ion exchange chromatography, Sephadex G-75 gel filtration, Q-Sepharose ion exchange chromatography, 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 heatstable. The protein had 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-hydroxyethyl disulfide with an optimum pH of 8.5. Its activity was greatly activated by monothiol compounds such as reduced glutathione and L-cysteine.
Cho
Y W
YW
Division of Life Sciences, Kangwon National University, Chuncheon, Korea.
Kim
J C
JC
Jin
C D
CD
Han
T J
TJ
Lim
C J
CJ
D017360:Arabidopsis / Q000187:drug effects / Q000201:enzymology*; D003545:Cysteine / Q000494:pharmacology; D004229:Dithiothreitol / Q000494:pharmacology; D004789:Enzyme Activation / Q000187:drug effects; D004795:Enzyme Stability; D054477:Glutaredoxins; D005978:Glutathione / Q000494:pharmacology; D006358:Hot Temperature; D006863:Hydrogen-Ion Concentration; D007526:Isoelectric Point; D008623:Mercaptoethanol / Q000494:pharmacology; D008970:Molecular Weight; D010088:Oxidoreductases / Q000737:chemistry / Q000187:drug effects / Q000302:isolation & purification*; D011490:Protein Disulfide Reductase (Glutathione); D012639:Seeds / Q000187:drug effects / Q000201:enzymology*; D013379:Substrate Specificity; D013439:Sulfhydryl Reagents / Q000494:pharmacology
D054477:Glutaredoxins; D013439:Sulfhydryl Reagents; D008623:Mercaptoethanol; D010088:Oxidoreductases; D011490:Protein Disulfide Reductase (Glutathione); D005978:Glutathione; D003545:Cysteine; D004229:Dithiothreitol