| Co-Investigator(Kenkyū-buntansha) |
NISHIKIMI Moromitsu Wakayama Medical University, Department of Biochemistry, Professor, 医学部, 教授 (20022816)
INAI Yooko Wakayama Medical University, Department of Biochemistry, Assistant Professor, 医学部, 助手 (20316087)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 2003: ¥900,000 (Direct Cost: ¥900,000)
Fiscal Year 2002: ¥1,000,000 (Direct Cost: ¥1,000,000)
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| Research Abstract |
1.It is recognized that copper ions catalyze the reductive decomposition of S-nitrosothiols to yield NO. The amino-terminal part of prion protein is known to bind copper ions. In this study, we investigated whether copper-bound PrP_<23-98> catalyzes the release of NO from S-nitrosothiols. Correcting the reaction by free copper, which was released from copper-loaded PrP_<23-98> in the presence of S-nitrosoglutathione, We could definitively show the breakdown of S-nitrosoglutathione to form NO by PrP_<23-98>-bound copper. Furthermore, it was shown that the release of NO completely inhibited by copper chelators.
2.The amino-terminal part of prion protein, containing a series of octapeptide repeats with the consensus sequence PHGGGWGQ. has been shown to bind copper ion. In this study, we have investigated copper-catalyzed oxidation of mouse prion protein, PrP_<23-231> (PrP). The copper-loaded PrP was found to produce carbonyls by incubation with L-ascorbate, glutathione, and dopamine, whereas no significant increase in carbonyl was observed in their absence. To ascertain the participation of copper and reactive oxygen species in the formation of carbonyls on copper-loaded PrP, the inhibitory effect of various copper chelators, catalase, and SOD were tested. The inhibition was totally or nearly complete depending on the kind of the copper chelators. Catalase and SOD also inhibited the carbonyl formation, albeit to lesser extents. It was also noted that the copper-loaded PrP produced oligomerization and fragmentation when incubated with L-ascorbate or dopamine. The copper chelators, catalase, and SOD inhibited these phenomena as well. Taken together, these results indicate that the copper ions bound to PrP are redox-active in the presence of reducing substances and induce the oxidative damage to PrP.
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