Structure and mechanism of lipoxygenases

Prigge, Sean T.; Boyington, Jeffrey C.; Faig, M.; Doctor, Kutbuddin S.; Gaffney, Betty J.; Amzel, L. Mario

doi:10.1016/s0300-9084(97)83495-5

Cited by 117 publications

(106 citation statements)

References 26 publications

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“…FLAP serves to both stabilize the 5-LO enzyme and present it with AA substrate [18]. Similar studies with 15-LOa failed to demonstrate the presence of a specific 15-LOa docking protein, but instead suggested that 15-LOa interacts directly with membrane q FEBS 1999 phospholipids [16]. Direct interaction of 15-LOa with membranes may account for the observation that 15-LOa oxygenates complex lipid protein assemblies such as biomembranes, whereas 5-LO strongly prefers free AA as a substrate [19].…”

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confidence: 54%

“…For example, 12-HETE and 15-HETE have been implicated in tumour metastases and the formation of atherosclerotic plaques, respectively [11,12]. The important biological roles of these LO metabolites and the complexity of substrate utilization by members of the LO family emphasize the importance of understanding factors which affect the activity and regulation of these enzymes.Overexpression and characterization of recombinant 5-LO, 12-LO and 15-LOa have been carried out allowing kinetic analysis of these enzymes [9,13,14] and the hypotheses as to the mechanism by which LOs oxygenate fatty acids have been developed [15]. In vitro, both 5-LO and 15-LOa undergo a burst phase of activity before reaching a steady rate of product formation and then undergoing suicide inactivation by their respective enzyme products [9,14].…”

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confidence: 99%

“…Overexpression and characterization of recombinant 5-LO, 12-LO and 15-LOa have been carried out allowing kinetic analysis of these enzymes [9,13,14] and the hypotheses as to the mechanism by which LOs oxygenate fatty acids have been developed [15]. In vitro, both 5-LO and 15-LOa undergo a burst phase of activity before reaching a steady rate of product formation and then undergoing suicide inactivation by their respective enzyme products [9,14].…”

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confidence: 99%

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Differential characteristics of human 15‐lipoxygenase isozymes and a novel splice variant of 15S‐lipoxygenase

Kilty

Logan

Vickers

1999

European Journal of Biochemistry

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The lipoxygenases (LOs) are a family of nonheme iron dioxygenases that catalyse the insertion of molecular oxygen into polyunsaturated fatty acids. Five members of this gene family have been described in man, 5-LO, 12S-LO, 12R-LO, 15-LO and 15S-LO. Using partially purified recombinant 15S-LO enzyme and cells constitutively expressing this protein, we have compared the activity, substrate specificity, kinetic characteristics and regulation of this enzyme to that previously reported for 15-LO. 15S-LO has a threefold higher K m , similar V max and increased specificity of oxygenation for arachidonic acid, and a similar K m but decreased V max for linoleic acid in comparison to 15-LO. Unlike 15-LO, 15S-LO is not suicide inactivated by the products of fatty acid oxygenation. However, in common with other LOs, 15S-LO activity is regulated through calcium-dependent association of the enzyme with the membrane fraction of cells.In addition, whilst independently cloning the recently described 15S-LO, we identified a splice variant containing an in-frame 87-bp deletion corresponding to amino acids 401±429 inclusive. Modelling of the 15S-LO and subsequent studies with partially purified recombinant protein suggest that the deleted region comprises a complete a-helix flanking the active site of the enzyme resulting in decreased specificity of oxygenation and affinity for fatty acid substrates.Alternative splicing of 15S-LO would therefore provide a further level of regulation of fatty acid metabolism. These results demonstrate that there are substantial differences in the enzyme characteristics and regulation of the 15-LO isozymes which may reflect differing roles for the proteins in vivo. Although the LOs produce specific hydroxyeicosatetraenoic (HETE) enantiomers, the enzymes do not all display absolute positional specificity with respect to oxygenation of AA. For example, while 15-LOb exclusively oxygenates C15 of AA [8], 15-LOa oxygenates AA at both C15 and C12 [9]. In addition, the degree of homology between members of the LO family does not define the product profile. For example, amino acid sequence alignments demonstrate that 15-LOb is more closely related to 12R-LO than 15-LOa, suggesting complex evolutionary paths in the LO family.The LOs are responsible for the synthesis of a number of inflammatory mediators, including leukotrienes and lipoxins, which are implicated in inflammatory disorders such as bronchial asthma [10]. Lipoxygenase metabolites have also been implicated in a number of noninflammatory biological processes. For example, 12-HETE and 15-HETE have been implicated in tumour metastases and the formation of atherosclerotic plaques, respectively [11,12]. The important biological roles of these LO metabolites and the complexity of substrate utilization by members of the LO family emphasize the importance of understanding factors which affect the activity and regulation of these enzymes.Overexpression and characterization of recombinant 5-LO, 12-LO and 15-LOa have been carried out allowing kinetic analysis...

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confidence: 54%

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confidence: 99%

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confidence: 99%

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Differential characteristics of human 15‐lipoxygenase isozymes and a novel splice variant of 15S‐lipoxygenase

Kilty

Logan

Vickers

1999

European Journal of Biochemistry

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“…2,3 There are three major human LOs (hLOs), 5-, 12-, and 15-hLO, whose main difference is the position of dioxygen incorporation into arachidonic acid (AA) (C-5, C-12, or C-15). 4,5 These three hLO isozymes are of great interest to scientists because they have been shown to be involved in a variety of diseases; 5-hLO in prostate cancer 6,7 and asthma 8 , 12-hLO in immune disorders 9 and breast cancer 7,10,11 , and 15-hLO-1 in atherosclerosis 12 and colorectal cancer. 7,13 Due to their involvement in such diseases, a better understanding of the mode of inhibition of small molecules is necessary to aid in future rational drug design against specific LO isozymes.…”

Section: Introductionmentioning

confidence: 99%

Baicalein is a potent in vitro inhibitor against both reticulocyte 15-human and platelet 12-human lipoxygenases

Deschamps

Kenyon

Holman

2006

Bioorganic & Medicinal Chemistry

144

125

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Abstract. Lipoxygenases (LO) have been implicated in asthma, immune disorders, and various cancers and as a consequence, there is great interest in isolating selective LO isozyme inhibitors.Currently, there is much use of baicalein as a selective human platelet 12-LO (12-hLO) inhibitor however, our current steady-state inhibition data indicates that baicalein is not selective against 12-hLO versus human reticulocyte 15-LO-1 (15-hLO-1) (15/12 = 1.3), in vitro. However, in the presence of detergents baicalein is slightly more selective (15/12 = 7), which may imply greater selectivity in a cell based assay but has yet to be proven. The mechanism of baicalein inhibition of 15-hLO is reductive, which computer docking suggests is through direct binding of the catecholic moiety of baicalein to the iron. A structurally related flavonoid, apigenin, is not reductive, however, computer docking suggests a hydrogen bond with Thr591, may account for its inhibitor potency.

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“…The products of these enzymes are responsible for variety of human disorders such as allergies, infl ammations, asthma, psoriasis, hypersensitivity [6,7] and atherosclerosis [8,9]. Hence inhibitors against this group of enzymes have great potential in food and health sectors.…”

Section: Introductionmentioning

confidence: 99%

Strain improvement of Aspergillus niger for the enhanced production of asperenone

2008

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The enhancement of production of asperenone ( Fig. 1), an inhibitor of lipoxygenase and human platelet aggregation from Aspergillus niger CFTRI 1105, was achieved by UV and nitrous acid mutagenesis. Nitrous acid mutants exhibited increased inhibitor production when compared with UV irradiated mutants. I N 41 a fi rst-generation nitrous acid mutant produced 5.1 fold increased asperenone over parent strain. Mutant II N 31 obtained by second-generation nitrous acid treatment produced 60.3 mg asperenone/g biomass, which was 131 fold increase when compared to fi rst generated mutant I N 41 and 670 fold increase over the parent strain. This mutant was stable for several generations on production medium.

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Structure and mechanism of lipoxygenases

Cited by 117 publications

References 26 publications

Differential characteristics of human 15‐lipoxygenase isozymes and a novel splice variant of 15S‐lipoxygenase

Differential characteristics of human 15‐lipoxygenase isozymes and a novel splice variant of 15S‐lipoxygenase

Baicalein is a potent in vitro inhibitor against both reticulocyte 15-human and platelet 12-human lipoxygenases

Strain improvement of Aspergillus niger for the enhanced production of asperenone

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