[Thermoinactivation of potato 5-lipoxygenase and effect of phosphatidic acid on activation energy of denaturation].

The investigation aim was to establish the structural-functional relations of individual lipid metabolism components: enzymes--lipoxygenases and membrane phospholipids. Influence of phosphatidic acid (PA)--allosteric activator of potato tuber 5-lipoxygenase (5-LO)--on thermoinactivation thermodynamic parameters of enzyme was studied. It was established that PA changes essentially the 5-LO thermostability, namely activation energy Ea of enzyme denaturation increases several times in this phospholipid presence. Such changes can evidence that PA interaction with 5-LO leads to conformational changes of enzyme probably due to hydrophobic interactions. Obtained results give a possibility to interpret the action mechanism of PA as 5-LO allosteric activator, which can displace the substrate molecules in binding sites and increase the level of formation of specific products of linoleic acid oxygenation by 5-LO.