GSH-dependent peroxidase activity of the rice (Oryza sativa) glutaredoxin, a thioltransferase.
Glutaredoxin (Grx) is a 12-kDa thioltransferase that reduces disulfide bonds of other proteins and maintains the redox potential of cells. In addition to its oxidoreductase activity, we report here that a rice Grx (OsGrx) can also function as a GSH-dependent peroxidase. Because of this antioxidant activity, OsGrx protects glutamine synthetase from oxidative damage. Individually replacing the conserved Cys residues in OsGrx with Ser shows that Cys(23), but not Cys(26), is essential for the thioltransferase and GSH-dependent peroxidase activities. Kinetic characterization of OsGrx reveals that the maximal catalytic efficiency (V(max)/K(m)) is obtained with cumene hydroperoxide rather than H(2)O(2) or t-butyl hydroperoxide.
Division of Applied Life Sciences (BK21 program), Department of Biochemistry, PMBBRC, Gyeongsang National University, 660-701, Chinju, Republic of Korea.
Kyun Oh
KO
Lee
Jung Ro
JR
Lee
Ji Young
JY
Yoo
Ho Hee
HH
Jang
Jeong Chan
JC
Moon
Bae Gyo
BG
Jung
Yong Hun
YH
Chi
Soo Kwon
SK
Park
Seung Sik
SS
Lee
Chae Oh
CO
Lim
Dae-Jin
DJ
Yun
Moo Je
MJ
Cho
Sang Yeol
SY
Lee
D000975:Antioxidants / Q000378:metabolism; D003545:Cysteine / Q000235:genetics; D004591:Electrophoresis, Polyacrylamide Gel; D054477:Glutaredoxins; D005978:Glutathione / Q000502:physiology*; D007700:Kinetics; D009154:Mutation; D012275:Oryza / Q000201:enzymology*; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism*; D009195:Peroxidase / Q000235:genetics / Q000378:metabolism*; D011490:Protein Disulfide Reductase (Glutathione); D013379:Substrate Specificity
D000975:Antioxidants; D054477:Glutaredoxins; D010088:Oxidoreductases; D009195:Peroxidase; D011490:Protein Disulfide Reductase (Glutathione); D005978:Glutathione; D003545:Cysteine