title: Effect of 4-hydroxy-2(E)-nonenal on soybean lipoxygenase-1.
abstract: The oxidation of linoleic acid by soybean lipoxygenase-1 (LOX-1) was inhibited in a time-dependent manner by 4-hydroxy-2(E)-nonenal (HNE). Kinetic analysis indicated the effect was due to slow-binding inhibition conforming to an affinity labeling mechanism-based inhibition. After 25 min of preincubation of LOX-1 with and without HNE, Lineweaver-Burk reciprocal plots indicated mixed noncompetitive/competitive inhibition. Low concentrations of HNE influenced the electron paramagnetic resonance (EPR) signal of 13(S)-hydroperoxy-9(Z), 11 (E)-octadecadienoic acid (13-HPODE)-generated Fe3+-LOX-1 slightly, but higher concentrations completely eliminated the EPR signal indicating an active site hindered from access by 13-HPODE. HNE may compete for the active site of LOX-1 because its precursor, 4-hydroperoxy-(2E)-nonenal, is a product of LOX-1 oxidation of (3Z)-nonenal. Also, it was an attractive hypothesis to suggest that HNE may disrupt the active site by forming a Michael adduct with one or more of the three histidines that ligate the iron active site of LOX-1.
authors.affiliation: Mycotoxin Research, NCAUR, ARS, USDA, Peoria, Illinois 61604, USA. gardnehw@mail.ncaur.usda.gov
authors.forename: H W
authors.initials: HW
authors.lastname: Gardner
authors.forename: N
authors.initials: N
authors.lastname: Deighton
mesh_terms: D000447:Aldehydes / Q000737:chemistry / Q000494:pharmacology*; D002021:Buffers; D020134:Catalytic Domain; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology*; D004578:Electron Spin Resonance Spectroscopy; D004789:Enzyme Activation / Q000187:drug effects; D006639:Histidine; D019787:Linoleic Acid / Q000737:chemistry / Q000378:metabolism; D008041:Linoleic Acids / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D008054:Lipid Peroxides / Q000032:analysis / Q000737:chemistry / Q000378:metabolism; D008084:Lipoxygenase / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D016859:Lipoxygenase Inhibitors / Q000737:chemistry / Q000494:pharmacology*
chemical_list: D000447:Aldehydes; D002021:Buffers; D015853:Cysteine Proteinase Inhibitors; D008041:Linoleic Acids; D008054:Lipid Peroxides; D016859:Lipoxygenase Inhibitors; C038649:13-hydroperoxy-9,11-octadecadienoic acid; D006639:Histidine; D019787:Linoleic Acid; D008084:Lipoxygenase; C027576:4-hydroxy-2-nonenal