title: Mg2+ activates 5-lipoxygenase in vitro: dependency on concentrations of phosphatidylcholine and arachidonic acid.
abstract: Mg2+ gave dose-dependent activation of 5-lipoxygenase (5LO) in vitro. As for Ca2+, the activation depended on the presence of phosphatidylcholine (PC) vesicles, and the activation response was different at various combinations of arachidonate and PC. Stimulation of 5LO activity was observed with Mg2+ concentrations of 0.1-1 mM, similar to the concentration range of free Mg2+ in mammalian cells. However, to observe a clear increase in 5LO hydrophobicity, a higher concentration of Mg2+ (4 mM) was required, and at this concentration also 5LO activation was optimal. Combinations of Mg2+ with ATP (containing free Mg2+ and MgATP2- complex) gave better activation of 5LO than either agent alone. This effect of Mg2+ (and ATP) could be of interest in relation to basal 5LO activity in cells not subjected to a particular stimulus.
authors.affiliation: Department of Medical Biochemistry and Biophysics, Division of Chemistry II, Karolinska Institute, S-17177, Stockholm, Sweden.
authors.forename: K V
authors.initials: KV
authors.lastname: Reddy
authors.forename: T
authors.initials: T
authors.lastname: Hammarberg
authors.forename: O
authors.initials: O
authors.lastname: Rådmark
mesh_terms: D000255:Adenosine Triphosphate / Q000737:chemistry / Q000494:pharmacology; D001094:Arachidonate 5-Lipoxygenase / Q000737:chemistry* / Q000235:genetics / Q000302:isolation & purification; D016718:Arachidonic Acid / Q000737:chemistry; D001095:Arachidonic Acids / Q000737:chemistry*; D002118:Calcium / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation; D020536:Enzyme Activators / Q000737:chemistry*; D005822:Genetic Vectors / Q000378:metabolism; D006801:Humans; D008274:Magnesium / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry*; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification; D014867:Water / Q000737:chemistry
chemical_list: D001095:Arachidonic Acids; D020536:Enzyme Activators; D010713:Phosphatidylcholines; D011994:Recombinant Proteins; D014867:Water; D016718:Arachidonic Acid; D000255:Adenosine Triphosphate; D001094:Arachidonate 5-Lipoxygenase; D008274:Magnesium; D002118:Calcium