title: Reactive nitrogen species derived activation of rat liver microsomal glutathione S-transferase.
abstract: The effect of reactive nitrogen species on rat liver microsomal glutathione S-transferase (MGST1) was investigated using microsomes and purified MGST1. When microsomes or the purified enzyme were incubated with peroxynitrite (ONOO(-)), the GST activity was increased to 2.5-6.5 fold in concentration-dependent manner and a small amount of the MGST1 dimer was detected. MGST1 activity was increased by ONOO(-) in the presence of high amounts of reducing agents including glutathione (GSH) and the activities increased by ONOO(-) or ONOO(-) plus GSH treatment were decreased by 30-40% by further incubation with dithiothreitol (DTT, reducing disulfide) or by sodium arsenite (reducing sulfenic acid). Furthermore, GSH was detected by HPLC from the MGST1 which was incubated with ONOO(-) plus GSH or S-nitrosoglutathione followed by DTT treatment. In addition, the MGST1 activity increased by nitric oxide (NO) donors such as S-nitrosoglutathione, S-nitrosocysteine or the non-thiol NO donor 1-hydroxy-2-oxo-3 (3-aminopropyl)-3-isopropyl was restored by the DTT treatment. Since DTT can reduce S-nitrosothiol and disulfide bond to thiol, S-nitrosylation and a mixed disulfide bond formation of MGST1 were suggested. Thus, it was demonstrated that MGST1 is activated by reactive nitrogen species through a forming dimeric protein, mixed disulfide bond, nitrosylation and sulfenic acid.
authors.affiliation: Laboratory of Functional and Molecular Pharmacology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan.
authors.forename: Naoki
authors.initials: N
authors.lastname: Imaizumi
authors.forename: Suzuyo
authors.initials: S
authors.lastname: Miyagi
authors.forename: Yoko
authors.initials: Y
authors.lastname: Aniya
mesh_terms: D000818:Animals; D015153:Blotting, Western; D004229:Dithiothreitol / Q000494:pharmacology; D005982:Glutathione Transferase / Q000378:metabolism*; D066298:In Vitro Techniques; D008297:Male; D008862:Microsomes, Liver / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D010084:Oxidation-Reduction; D051381:Rats; D017207:Rats, Sprague-Dawley; D026361:Reactive Nitrogen Species / Q000378:metabolism*; D026422:S-Nitrosoglutathione / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013439:Sulfhydryl Reagents / Q000494:pharmacology
chemical_list: D020030:Nitric Oxide Donors; D026361:Reactive Nitrogen Species; D013438:Sulfhydryl Compounds; D013439:Sulfhydryl Reagents; D026422:S-Nitrosoglutathione; D005982:Glutathione Transferase; D004229:Dithiothreitol