The 6R-oxygenase activity of arachidonate 5-lipoxygenase purified from porcine leukocytes.
Arachidonate 5-lipoxygenase purified from porcine leukocytes was incubated with (5S)-hydroperoxy-6,8,11,14-eicosatetraenoic acid. In addition to degradation products of leukotriene A4 (6-trans-leukotriene B4 and its 12-epimer and others), (5S,6R)-dihydroperoxy-7,9,11,14-eicosatetraenoic acid was produced as a major product especially when the incubation was performed on ice rather than at room temperature. The amount of the (5S,6R)-dihydroperoxy acid was close to the total amount of leukotriene A4 degradation products. Under the anaerobic condition, production of the (5S,6R)-dihydroperoxy acid was markedly reduced. 5-Hydroxy-6,8,11,14-eicosatetraenoic acid could be a substrate of the enzyme and was transformed predominantly to a compound identified as (5S)-hydroxy-(6R)-hydroperoxy-7,9-trans-11,14-cis-eicosatetraenoic acid at about 1-2% rate of arachidonate 5-oxygenation. These findings indicated that the purified 5-lipoxygenase exhibited a 6R-oxygenase activity with (5S)-hydroxy and (5S)-hydroperoxy acids as substrates. The 6R-oxygenase activity, like the leukotriene A synthase activity, was presumed to be an integral part of 5-lipoxygenase because it required calcium and ATP and was affected by selective 5-lipoxygenase inhibitors.
Ueda
N
N
Department of Biochemistry, Tokushima University School of Medicine, Japan.
Yamamoto
S
S
D000818:Animals; D001094:Arachidonate 5-Lipoxygenase / Q000097:blood*; D001091:Arachidonate Lipoxygenases / Q000097:blood*; D001095:Arachidonic Acids / Q000097:blood; D002851:Chromatography, High Pressure Liquid; D006893:Hydroxyeicosatetraenoic Acids / Q000097:blood; D007962:Leukocytes / Q000201:enzymology*; D015289:Leukotrienes; D008054:Lipid Peroxides / Q000097:blood; D010105:Oxygenases / Q000097:blood*; D013056:Spectrophotometry, Ultraviolet; D013552:Swine
D001095:Arachidonic Acids; D006893:Hydroxyeicosatetraenoic Acids; D015289:Leukotrienes; D008054:Lipid Peroxides; C022022:5-hydroxy-6,8,11,14-eicosatetraenoic acid; C025086:15-hydroperoxy-5,8,11,13-eicosatetraenoic acid; C025348:arachidonic acid 5-hydroperoxide; D010105:Oxygenases; D001091:Arachidonate Lipoxygenases; D001094:Arachidonate 5-Lipoxygenase