title: Activation of 5-lipoxygenase by guanosine 5'-O-(3-thiotriphosphate) and other nucleoside phosphorothioates: redox properties of thionucleotide analogs.
abstract: The stable nucleotide analog guanosine 5'-O-(3-thiotriphosphate) (GTP gamma S) was found to be a very potent activator of 5-lipoxygenase in cell-free preparations from rat polymorphonuclear (PMN) leukocytes, causing a 10-fold stimulation of arachidonic acid oxidation at concentrations as low as 0.5-1 microM. The enhancement of enzyme activity was not directly related to G protein activation since the effect of GTP gamma S could not be abolished by GDP nor replaced by GTP or guanylyl-imidodiphosphate (up to 100 microM). Furthermore, other phosphorothioate analogs, such as guanosine 5'-O-(2-thiodiphosphate), adenosine 5'-O-(3-thiotriphosphate), adenosine 5'-O-(2-thiodiphosphate), and adenosine 5'-O-thiomonophosphate all stimulated 5-lipoxygenase activity at concentrations of 10 microM or lower. This effect could not be detected with any of the corresponding nucleoside phosphate derivatives. The stimulation of 5-lipoxygenase activity by nucleoside phosphorothioates was observed under conditions where the reaction is highly dependent on exogenous hydroperoxides, such as in the presence of beta-mercaptoethanol or using enzyme preparations pretreated with sodium borohydride or glutathione peroxidase. GTP gamma S stimulated arachidonic acid oxidation by 5-lipoxygenase to the same extent as the activating hydroperoxides but had no effect on the reaction measured in the presence of optimal concentrations of 13-hydroperoxyoctadecadienoic acid (1-5 microM). Finally, sodium thiophosphate, but not sodium phosphate, markedly stimulated 5-lipoxygenase activity with properties similar to those of GTP gamma S. These results indicate that GTP gamma S and other phosphorothioate derivatives have redox properties that can contribute to increase 5-lipoxygenase activity by replacing the effect of hydroperoxides.
authors.affiliation: Merck Frosst Centre for Therapeutic Research, Pointe Claire-Dorval, Quebec, Canada.
authors.forename: D
authors.initials: D
authors.lastname: Denis
authors.forename: L Y
authors.initials: LY
authors.lastname: Choo
authors.forename: D
authors.initials: D
authors.lastname: Riendeau
mesh_terms: D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000378:metabolism*; D001091:Arachidonate Lipoxygenases / Q000378:metabolism*; D002853:Chromatography, Liquid; D004789:Enzyme Activation; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate / Q000031:analogs & derivatives* / Q000494:pharmacology; D010084:Oxidation-Reduction; D010545:Peroxides / Q000494:pharmacology; D010710:Phosphates / Q000494:pharmacology; D010770:Phosphotransferases / Q000494:pharmacology*; D051381:Rats; D013873:Thionucleotides / Q000494:pharmacology*
chemical_list: D010545:Peroxides; D010710:Phosphates; D013873:Thionucleotides; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D006160:Guanosine Triphosphate; D001091:Arachidonate Lipoxygenases; D001094:Arachidonate 5-Lipoxygenase; D010770:Phosphotransferases; C021892:nucleoside phosphotransferase; C035638:thiophosphoric acid