title: Irreversible inactivation of magnesium-dependent neutral sphingomyelinase 1 (NSM1) by peroxynitrite, a nitric oxide-derived oxidant.
abstract: Previous results have indicated that the generation of ceramide by hydrolysis of sphingomyelin by magnesium-dependent neutral sphingomyelinase 1 (NSM1) is reversibly inhibited by hydrogen peroxide (H2O2) and oxidized glutathione (GSSG). This redox-dependent reversible regulation of NSM1 activity has been shown to involve the reversible formation and breakage of disulfide bonds. In this paper, we show that peroxynitrite, a nitric oxide-derived oxidant generated by SIN1, inactivates dose-dependently the NSM1 activity in an irreversible manner. In addition, we show that, in contrast to the reversible inhibition of NSM1 by H2O2 or GSSG which involves the formation of disulfide bonds, irreversible inactivation of this enzyme by peroxynitrite generated from SIN1 is likely due to definitive oxidative thiol modification. These results suggest that depending on the nature of the oxidative stress, the enzymatic activity of NSM1 could be reversibly or irreversibly inactivated.
authors.affiliation: Protein Biochemistry Group, Cancer Research UK Centre for Cell and Molecular Biology, The Institute of Cancer Research, Chester Beatty Laboratories, London, UK.
authors.forename: Michelle
authors.initials: M
authors.lastname: Josephs
authors.forename: Matilda
authors.initials: M
authors.lastname: Katan
authors.forename: Fernando
authors.initials: F
authors.lastname: Rodrigues-Lima
mesh_terms: D000818:Animals; D003545:Cysteine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006861:Hydrogen Peroxide / Q000494:pharmacology; D008274:Magnesium / Q000502:physiology; D051379:Mice; D008981:Molsidomine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009569:Nitric Oxide / Q000378:metabolism; D020030:Nitric Oxide Donors / Q000494:pharmacology; D016877:Oxidants / Q000494:pharmacology*; D018384:Oxidative Stress; D030421:Peroxynitrous Acid / Q000096:biosynthesis / Q000494:pharmacology*; D019163:Reducing Agents / Q000494:pharmacology; D013108:Sphingomyelin Phosphodiesterase / Q000737:chemistry / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D020030:Nitric Oxide Donors; D016877:Oxidants; D019163:Reducing Agents; D030421:Peroxynitrous Acid; D009569:Nitric Oxide; C002385:linsidomine; D006861:Hydrogen Peroxide; D008981:Molsidomine; D013108:Sphingomyelin Phosphodiesterase; D008274:Magnesium; D003545:Cysteine