Egmond M R, Brunori M, Fasella P M
Eur J Biochem. 1976 Jan 2;61(1):93-100. doi: 10.1111/j.1432-1033.1976.tb10001.x.
The steady-state kinetics of the oxygenation of linoleic acid catalysed by soybean lipoxygenase-1 were studied. The results showed that lipoxygenase-1 is strongly inhibited by its substrate, linoleic acid. In the presence of the product of the reaction, 13-LS-hydroperoxy-linoleic acid, the substrate inhibition only affects the apparent affinity for O2 and is of a hyperbolic type. A kinetic scheme of the oxygenation reaction is presented, which postulates two substrate-binding sites on the enzyme, one for linoleic acid and one for O2, and a regulatory binding site, which can either bind the product or the fatty acid substrate. Since previous studies indicated that the product of the reaction influences the oxidation state of the iron present in protein, the steady-state kinetics of the native enzyme and of the enzyme pre-incubated with the product were compared. Pre-incubation of the enzyme with the product did not lead to altered steady-state kinetics of the reaction compared to those of the native enzyme.
研究了大豆脂氧合酶-1催化亚油酸氧化的稳态动力学。结果表明，脂氧合酶-1受到其底物亚油酸的强烈抑制。在反应产物13-LS-氢过氧亚油酸存在的情况下，底物抑制仅影响对O2的表观亲和力，且呈双曲线型。提出了氧化反应的动力学方案，该方案假定酶上有两个底物结合位点，一个用于亚油酸，一个用于O2，还有一个调节结合位点，它可以结合产物或脂肪酸底物。由于先前的研究表明反应产物会影响蛋白质中铁的氧化态，因此比较了天然酶和与产物预孵育的酶的稳态动力学。与天然酶相比，酶与产物预孵育不会导致反应稳态动力学发生改变。
