Lipoxygenases: Occurrence, Functions, Catalysis, and Acquisition of Substrate

Brash, Alan R.

doi:10.1074/jbc.274.34.23679

Cited by 1,208 publications

(991 citation statements)

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“…They are bioactive compounds involved in signal and defence reactions in mammals, higher plants and algae (Brash, 1999;Blee, 2002;Pohnert, 2005). The biosynthesis of many oxylipins is initiated by the conversion of PUFAs by a lipoxygenase (LOX) .…”

Section: Introductionmentioning

confidence: 99%

Lipid metabolism in arbuscular mycorrhizal roots of Medicago truncatula

Stumpe¹,

Carsjens²,

Stenzel

et al. 2005

Phytochemistry

118

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Section: Introductionmentioning

confidence: 99%

Lipid metabolism in arbuscular mycorrhizal roots of Medicago truncatula

Stumpe¹,

Carsjens²,

Stenzel

et al. 2005

Phytochemistry

118

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“…It has been suggested that the N-terminal domain in LOX-1 makes only a loose contact with the C-terminal domain (9), and that it may be also dispensable for plant lipoxygenases (10), because all the amino acid side chains responsible for catalysis are located in the C-terminal domain. However, limited proteolysis experiments indicated that the two domains are instead tightly associated (20), and that domain-domain interactions play a role in the reversible unfolding of LOX-1 (21,22), through ionic interactions (13). Despite these structural data, there is no clear evidence whether the N-terminal domain may affect lipoxygenase activity, with respect to the kinetic properties of the reaction and to the product specificity.…”

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confidence: 99%

Tryptic Digestion of Soybean Lipoxygenase-1 Generates a 60 kDa Fragment with Improved Activity and Membrane Binding Ability

et al. 2001

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Lipoxygenases are key enzymes in the metabolism of unsaturated fatty acids. Soybean lipoxygenase-1 (LOX-1), a paradigm for lipoxygenases isolated from different sources, is composed of two domains: a ∼30 kDa N-terminal domain and a ∼60 kDa C-terminal domain. We used limited proteolysis and gel-filtration chromatography to generate and isolate a ∼60 kDa fragment of LOX-1 ("mini-LOX"), produced by trypsin cleavage between lysine 277 and serine 278. Mini-LOX was subjected to N-terminal sequencing and to electrophoretic, chromatographic, and spectroscopic analysis. Mini-LOX was found to be more acidic and more hydrophobic than LOX-1, and with a higher content of R-helix. Kinetic analysis showed that mini-LOX dioxygenates linoleic acid with a catalytic efficiency approximately 3-fold higher than that of LOX-1 (33.3 × 10 6 and 10.9 × 10 6 M -1 ‚s -1 , respectively), the activation energy of the reaction being 4.5 ( 0.5 and 8.3 ( 0.9 kJ‚mol -1 for mini-LOX and LOX-1, respectively. Substrate preference, tested with linoleic, R-linolenic, and arachidonic acids, and with linoleate methyl ester, was the same for LOX-1 and mini-LOX, and also identical was the regio-and stereospecificity of the products generated thereof, analyzed by reversed-phase and chiral high-performance liquid chromatography, and by gas chromatography/mass spectrometry. Mini-LOX was able to bind artificial vesicles with higher affinity than LOX-1, but the binding was less affected by calcium ions than was that of LOX-1. Taken together, these results suggest that the N-terminal domain of soybean lipoxygenase-1 might be a built-in inihibitor of catalytic activity and membrane binding ability of the enzyme, with a possible role in physio-(patho)logical conditions.Lipoxygenases are a family of monomeric non-heme, nonsulfur iron dioxygenases which catalyze the conversion of unsaturated fatty acids into conjugated hydroperoxides. Mammalian lipoxygenases have been implicated in the pathogenesis of several inflammatory conditions such as arthritis, psoriasis, and bronchial asthma (1). They have been also implicated in atherosclerosis (2), brain aging (3), HIV infection (4), and kidney disease (5, 6). In plants, lipoxygenases favor germination and participate in the synthesis of traumatin and jasmonic acid and in the response to abiotic stress (7). Recently, they have been also shown to initiate the programmed death (apoptosis) of plant cells (8). Soybean lipoxygenase-1 (LOX-1) 1 is widely used as a prototype for studying the homologous family of lipoxygenases from tissues of different species, both in structural (9-13) and in kinetic (14-18) investigations. The amino acid sequence (19) and three-dimensional structure (9, 10) of LOX-1 have been determined. The overall 839 amino acid residues of LOX-1, with a molecular mass of 93 840 Da, show 2 domains. The first 146 N-terminal amino acid residues form an 8-stranded -barrel, and the remaining 693 residues of the C-terminal domain are organized into 23 helices and 8 -strands. Mammalian lipoxygenases do ...

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“…14,34 Recently, a new mechanism for O 2 activation in the presence of iron(III) was brought forward. Iron(III) interacted with the known charge-transfer complex formed between the substrate linoleic acid and O 2 leading to a ternary complex Fe III -O 2 -substrate, giving the substrate hydroperoxide product without change of the iron oxidation state.…”

Section: Rate Law and Oxidative Dehydrogenation Reaction Mechanismmentioning

confidence: 99%