Competitive inhibition of the 5-lipoxygenase-catalysed linoleate oxidation by arachidonic and 5-hydroperoxy-eicosatetraenoic acids

• Published in: FEBS letters Vol. 377; no. 3; pp. 306 - 308
• Main Authors: Mirzoeva, Olga K., Sud'ina, Galina F., Pushkareva, Marina A., Varfolomeev, Sergey D.
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 27.12.1995
• Subjects: 5-Lipoxygenase; Arachidonic acid; Arachidonic Acid - pharmacology; Enzyme Activation; Hordeum - enzymology; Hydrogen-Ion Concentration; Leukotrienes - pharmacology; Linoleic Acid; Linoleic Acids - metabolism; Linoleic Acids - pharmacology; Lipoxygenase Inhibitors - pharmacology; Substrate Specificity; AA; 5-LO; LA; 5-HPETE; 5-Lipoxygenase; Arachidonic acid; 9-HPODE; Linoleic acid
• ISSN: 0014-5793; 1873-3468
• DOI: 10.1016/0014-5793(95)01350-4

Linoleic and arachidonic acids are competing substrates for 5-1ipoxygenase from barley. When these two substrates are added simultaneously, arachidonic acid acts as a competitive inhibitor of linoleic acid oxidation with K i of 20 μM, the same value as the Michaelis constant for arachidonate oxygenation by this enzyme (22 ± 3 μM). 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 K i equal to 0.5 μM.