Poster: Oxidative stress

Abs # 91: GSH-dependent peroxidase activity of the rice (Oryza sativa) glutaredoxin, a thioltransferase

Presenter:	Kang, Jae Sook , kangjae76@nate.com
Authors	Kang, Jae Sook  (A)   Lee, Jung Ro  (A)   Chi, Yong Hun  (A)   Park, Soo Kwon  (A)   Lee, Seung Sik  (A)   Park, Jin Ho  (A)   Cho, Moo Je  (A)   Lee, Sang Yeol  (A)
Affiliations:	(A): Environmental Biotechnology Research Center

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 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 Cys23, but not Cys26, is essential for the thioltransferase and GSH-dependent peroxidase activities. Kinetic characterization of OsGrx reveals that the maximal reducing activity (Vmax) is obtained with t-butyl hydroperoxide rather than H2O2 and cumene hydroperoxide. [This work was supported by a grant from KoSEF to the EBRC (grant#:R15-2003-012-01001-0)]