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.
Lee
Kyun Oh
KO
Division of Applied Life Sciences (BK21 program), Department of Biochemistry, PMBBRC, Gyeongsang National University, 660-701, Chinju, Republic of Korea.
Lee
Jung Ro
JR
Yoo
Ji Young
JY
Jang
Ho Hee
HH
Moon
Jeong Chan
JC
Jung
Bae Gyo
BG
Chi
Yong Hun
YH
Park
Soo Kwon
SK
Lee
Seung Sik
SS
Lim
Chae Oh
CO
Yun
Dae-Jin
DJ
Cho
Moo Je
MJ
Lee
Sang Yeol
SY
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