On the mechanism of the oxygenation of arachidonic acid by human platelet lipoxygenase

Hámberg, Mats; Hamberg, Gunvor

doi:10.1016/0006-291x(80)91584-3

Cited by 126 publications

(34 citation statements)

References 7 publications

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“…Although the human platelet 12-LOX shares a high degree (65%) of amino acid conservation with the human 12/15-LOX, it oxygenates arachidonic acid exclusively to 12-H(p)ETE (32). A similar reaction specificity was previously reported for the recombinant enzyme (24), and we confirmed this result in our study (Fig.…”

Section: Mutagenesis Studies On Human Platelet 12-loxsupporting

confidence: 92%

Applicability of the Triad Concept for the Positional Specificity of Mammalian Lipoxygenases

Vogel

Jansen

Roffeis

et al. 2010

Journal of Biological Chemistry

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The nomenclature of lipoxygenases (LOXs) is partly based on the positional specificity of arachidonic acid oxygenation, but there is no unifying concept explaining the mechanistic basis of this enzyme property. According to the triad model, Phe-353, Ile-418, and Ile-593 of the rabbit 12/15-LOX form the bottom of the substrate-binding pocket, and introduction of less spacefilling residues at either of these positions favors arachidonic acid 12-lipoxygenation. The present study was aimed at exploring the validity of the triad concept for two novel primate 12/15-LOX (Macaca mulatta and Pongo pygmaeus) and for five known members of the mammalian LOX family (human 12/15-LOX, mouse 12/15-LOX, human 15-LOX2, human platelet type 12-LOX, and mouse (12R)-LOX). The enzymes were expressed as N-terminal His tag fusion proteins in E. coli, the potential sequence determinants were mutated, and the specificity of arachidonic acid oxygenation was quantified. Taken together, our data indicate that the triad concept explains the positional specificity of all 12/15-LOXs tested (rabbit, human, M. mulatta, P. pygmaeus, and mouse). For the new enzymes of M. mulatta and P. pygmaeus, the concept had predictive value because the positional specificity predicted on the basis of the amino acid sequence was confirmed experimentally. The specificity of the platelet 12-LOX was partly explained by the triad hypothesis, but the concept was not applicable for 15-LOX2 and (12R)-LOX.

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Section: Mutagenesis Studies On Human Platelet 12-loxsupporting

confidence: 92%

Applicability of the Triad Concept for the Positional Specificity of Mammalian Lipoxygenases

Vogel

Jansen

Roffeis

et al. 2010

Journal of Biological Chemistry

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“…We measured the retention of tritium in the 12R-HETE after incubation of psoriatic scales with arachidonic acid substrates containing a prochiral tritium label on the 10-carbon. Invariably, lipoxygenases catalyze a stereoselective oxygenation with removal of the prochiral hydrogen from the opposite face of the substrate (33)(34)(35)(36). This characteristic selectivity is not observed in P450-catalyzed reactions.…”

Section: Discussionmentioning

confidence: 99%

A 12 R -lipoxygenase in human skin: Mechanistic evidence, molecular cloning, and expression

Boeglin

Kim

Brash

1998

Proc. Natl. Acad. Sci. U.S.A.

161

138

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A recognized feature of psoriasis and other proliferative dermatoses is accumulation in the skin of the unusual arachidonic acid metabolite, 12R-hydroxyeicosatetraenoic acid (12R-HETE). This hydroxy fatty acid is opposite in chirality to the product of the well-known 12S-lipoxygenase and heretofore in mammals is known only as a product of cytochrome P450s. Here we provide mechanistic evidence for a lipoxygenase route to 12R-HETE in human psoriatic tissue and describe a 12R-lipoxygenase that can account for the biosynthesis. Initially we demonstrated retention of the C-12 deuterium of octadeuterated arachidonic acid in its conversion to 12R-HETE in incubations of psoriatic scales, indicating the end product is not formed by isomerization from 12S-H(P)ETE via the 12-keto derivative. Secondly, analysis of product formed from [10 R -3 H] and [10 S -3 H]-labeled arachidonic acids revealed that 12R-HETE synthesis is associated with stereospecific removal of the pro-R hydrogen from the 10-carbon of arachidonate. This result is compatible with 12R-lipoxygenase-catalyzed formation of 12R-HETE and not with a P450-catalyzed route to 12R-HETE in psoriatic scales. We cloned a lipoxygenase from human keratinocytes; the cDNA and deduced amino acid sequences share <50% identity to other human lipoxygenases. This enzyme, when expressed in Hela cells, oxygenates arachidonic acid to 12-HPETE, >98% 12R in configuration. The 12R-lipoxygenase cDNA is detectable by PCR in psoriatic scales and as a 2.5-kilobase mRNA by Northern analysis of keratinocytes. Identification of this enzyme extends the known distribution of R-lipoxygenases to humans and presents an additional target for potential therapeutic interventions in psoriasis.

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“…Lipoxygenase is not inhibited, and continues to oxygenate free arachidonate until it is no longer available (25). Thus, in the presence of aspirin, arachidonate is diverted toward hydroxy acid production (24,25).…”

Section: Introductionmentioning

confidence: 99%

Enhancement of mononuclear procoagulant activity by platelet 12-hydroxyeicosatetraenoic acid.

Lorenzet¹,

Niemetz²,

Marcus³

et al. 1986

J. Clin. Invest.

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On the mechanism of the oxygenation of arachidonic acid by human platelet lipoxygenase

Cited by 126 publications

References 7 publications

Applicability of the Triad Concept for the Positional Specificity of Mammalian Lipoxygenases

Applicability of the Triad Concept for the Positional Specificity of Mammalian Lipoxygenases

A 12 R -lipoxygenase in human skin: Mechanistic evidence, molecular cloning, and expression

Enhancement of mononuclear procoagulant activity by platelet 12-hydroxyeicosatetraenoic acid.

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