Purification and characterization of glutaredoxin (thioltransferase) from rice (Oryza sativa L.).
We purified and characterized glutaredoxin (thioltransferase), which catalyzes thiol/disulfide exchange reaction, for the first time in plants. The purification procedure employed an immunoabsorbent, antiglutaredoxin-Sepharose. Glutaredoxin was purified about 2,200-fold from rice bran and it appeared to be homogeneous on SDS-PAGE. MALDI-TOF mass spectrometry revealed that the protein has a molecular mass of 11,097.9 Da. Rice glutaredoxin consists of 105 amino acid residues, containing the tetrapeptide -Cys-Phe-Pro (Tyr)-Cys-, which constitutes the active site of Escherichia coli and mammalian glutaredoxins. Inactivation assay also indicated that cysteine residues are responsible for enzyme activity. Kinetic analyses revealed that the enzyme did not exhibit normal Michaelis-Menten kinetics. The enzyme has an optimum pH of about 8.7 with 2-hydroxyethyl disulfide as a substrate. In addition, rice glutaredoxin has dehydroascorbate reductase activity, like mammalian glutaredoxin.
Sha
S
S
Department of Biochemistry, College of Agriculture, Kyoto Prefectural University, Shimogamo.
Minakuchi
K
K
Higaki
N
N
Sato
K
K
Ohtsuki
K
K
Kurata
A
A
Yoshikawa
H
H
Kotaru
M
M
Masumura
T
T
Ichihara
K
K
Tanaka
K
K
D000595:Amino Acid Sequence; D000937:Antigen-Antibody Reactions / Q000276:immunology; D004789:Enzyme Activation / Q000502:physiology; D054477:Glutaredoxins; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008969:Molecular Sequence Data; D009500:Neutralization Tests; D012275:Oryza / Q000201:enzymology*; D010088:Oxidoreductases / Q000032:analysis* / Q000302:isolation & purification* / Q000378:metabolism; D010940:Plant Proteins / Q000032:analysis / Q000302:isolation & purification; D011490:Protein Disulfide Reductase (Glutathione)
D054477:Glutaredoxins; D010940:Plant Proteins; D010088:Oxidoreductases; D011490:Protein Disulfide Reductase (Glutathione); C020666:glutathione dehydrogenase (ascorbate)