bpl-201201-0016 ArticleInAPeriodical 2012 Biologia plantarum 56 1 https://bp.ueb.cas.cz/artkey/bpl-201201-0016.php https://doi.org/10.1007/s10535-012-0023-4 105-110 VankoM. RauováD. BezákováL. HolkováI. BilkaF. CupákováM. Biochemical properties of lipoxygenase from opium poppy chloroplasts Lipoxygenase (LOX) from opium poppy (Papaver somniferum L.) chloroplasts was isolated and 126.1-fold purified to electrophoretic homogeneity by combination of ion-exchange chromatography on HA-Ultragel column and affinity chromatography on a linoleyl-aminopropyl agarose column. The relative molecular mass of the LOX determined by SDS-PAGE was 92 kDa. Kinetic properties of purified LOX were determined in spectrophotometric assay by using of linoleic acid (K<sub>M</sub> = 1.78 mM and V<sub>max</sub> = 11.4 μmol mg<sup>-1</sup> min<sup>-1</sup>) and linolenic acid (K<sub>M</sub> = 1.27 mM and V<sub>max</sub> = 10.2 μmol mg<sup>-1</sup> min<sup>-1</sup>). The optimum pH was 6.0 for both linoleic and linolenic acid dioxygenation catalyzed by LOX. HPLC analysis of the products revealed a dual positional specificity of linoleic acid dioxygenation at pH 6.0 with ratio of 9- and 13-hydroperoxide products being about 1:1. The activity of purified LOX was stimulated by Mg<sup>2+</sup> and Ca<sup>2+</sup>.