Vanko M. author Rauová D. author Bezáková L. author Holková I. author Bilka F. author Cupáková M. author text journal article 2012 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_M = 1.78 mM and V_max = 11.4 μmol mg^-1 min^-1) and linolenic acid (K_M = 1.27 mM and V_max = 10.2 μmol mg^-1 min^-1). 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 Mg²⁺ and Ca²⁺. fatty acid dioxygenation; oxylipin biosynthesis; Papaver somniferum; stress signaling 10.1007/s10535-012-0023-4 https://bp.ueb.cas.cz/artkey/bpl-201201-0016.php https://bp.ueb.cas.cz/artkey/bpl-201201-0016.php continuing 56 1 105 110 2012 periodical academic journal