Thiol-linked peroxidase activity of human sensitive to apoptosis gene (SAG) protein.
SAG (sensitive to apoptosis gene), a novel zinc RING finger protein, which is redox responsive and protects mammalian cells from apoptosis, is a metal chelator and a potential reactive oxygen species (ROS) scavenger, but its antioxidant properties have not been completely defined. Here, we show that SAG possesses a potent peroxidase property to decompose hydrogen peroxide in the presence of dithiothreitol (DTT). However, without DTT as a reducing equivalent, SAG was not able to destroy hydrogen peroxide. The peroxidase activity was completely abolished by the reaction of SAG with N-ethylmaleimide (NEM), a chemical modification agent for the sulfhydryl of proteins. These observations suggested that the sulfhydryl of cysteines in SAG could function as strong nucleophiles to destroy hydrogen peroxide. In addition to the peroxidase activity used to remove hydrogen peroxide, SAG also showed t-butylhydroperoxide (t-BOOH) and fatty acid hydroperoxide-selective peroxidase activity.
Kim
Sun Yee
SY
Department of Biochemistry, College of Natural Sciences, Kyungpook National University, Taegu, South Korea.
Bae
Young Seuk
YS
Park
Jeen-Woo
JW
D017209:Apoptosis; D004229:Dithiothreitol / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D005033:Ethylmaleimide / Q000494:pharmacology; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007700:Kinetics; D009195:Peroxidase / Q000378:metabolism*; D016601:RNA-Binding Proteins / Q000378:metabolism*; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism*; D013997:Time Factors; D044767:Ubiquitin-Protein Ligases; D016335:Zinc Fingers; D020122:tert-Butylhydroperoxide / Q000494:pharmacology
D016601:RNA-Binding Proteins; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D013438:Sulfhydryl Compounds; D020122:tert-Butylhydroperoxide; D006861:Hydrogen Peroxide; D009195:Peroxidase; C118307:RNF7 protein, human; D044767:Ubiquitin-Protein Ligases; D005033:Ethylmaleimide; D004229:Dithiothreitol