Competitive inhibition of the 5-lipoxygenase-catalysed linoleate oxidation by arachidonic and 5-hydroperoxy-eicosatetraenoic acids.
Linoleic and arachidonic acids are competing substrates for 5-lipoxygenase from barley. When these two substrates are added simultaneously, arachidonic acid acts as a competitive inhibitor of linoleic acid oxidation with Ki of 20 microM, the same value as the Michaelis constant for arachidonate oxygenation by this enzyme (22 +/- 3 microM). Linoleic acid hydroperoxide accumulated in the reaction mixture does not inhibit the enzymatic process, while arachidonic acid hydroperoxy product (5-hydroperoxy-6,8,11,14-eicosatetraenoic acid) inhibits it with very low Ki equal to 0.5 microM.
A.N. Belozersky Institute of Physico-Chemical Biology, Moscow State University, Russian Federation.
O K
OK
Mirzoeva
G F
GF
Sud'ina
M A
MA
Pushkareva
S D
SD
Varfolomeev
D016718:Arachidonic Acid / Q000494:pharmacology*; D004789:Enzyme Activation; D001467:Hordeum / Q000201:enzymology; D006863:Hydrogen-Ion Concentration; D015289:Leukotrienes / Q000494:pharmacology*; D019787:Linoleic Acid; D008041:Linoleic Acids / Q000378:metabolism* / Q000494:pharmacology*; D016859:Lipoxygenase Inhibitors / Q000494:pharmacology*; D013379:Substrate Specificity
D015289:Leukotrienes; D008041:Linoleic Acids; D016859:Lipoxygenase Inhibitors; D016718:Arachidonic Acid; C049606:9-hydroperoxy-11,12-octadecadienoic acid; C025348:arachidonic acid 5-hydroperoxide; D019787:Linoleic Acid