Disease relevance of Propadienylidene

• This reactive oxylipin was produced in barley seeds by oxygenation of linoleic acid by 9-lipoxygenase followed by dehydration of the resulting hydroperoxide by allene oxide synthase [1].

High impact information on Propadienylidene

• Purification of an allene oxide synthase and identification of the enzyme as a cytochrome P-450 [2].
• Fatty acid hydroperoxides (lipoxygenase products) are metabolized to allene oxides by a type of dehydrase that has been detected in plants, corals, and starfish oocytes [2].
• The structure of coral allene oxide synthase reveals a catalase adapted for metabolism of a fatty acid hydroperoxide [3].
• Allene oxide cyclase (EC ) catalyzes the stereospecific cyclization of an unstable allene oxide to (9S,13S)-12-oxo-(10,15Z)-phytodienoic acid, the ultimate precursor of jasmonic acid [4].
• Evidence of a cyclooxygenase-related prostaglandin synthesis in coral. The allene oxide pathway is not involved in prostaglandin biosynthesis [5].

Biological context of Propadienylidene

• Formation of the allene oxide was deduced from high pressure liquid chromatography, UV, gas chromatography-mass spectrometry and 1H-NMR analyses of the precise structure and mechanism of biosynthesis of its major hydrolysis product, the alpha-ketol 8-hydroxy-9-ketoeicosa-(5Z,11Z,14Z)-trienoic acid [6].
• Aspirin inhibition and acetylation of the plant cytochrome P450, allene oxide synthase, resembles that of animal prostaglandin endoperoxide H synthase [7].
• The most obvious similarities were: (a) down-regulation of several photosynthesis-related genes, and (b) up-regulation of genes involved in fatty acid metabolism and oxylipin biosynthesis such as HPL (hydroperoxide lyase), alpha-DIOX (alpha-dioxygenase), LOX (13-lipoxygenase), and AOS (allene oxide synthase) [8].
• It is proposed that inactivation involves elimination of HF to form an allene, which reacts with a nucleophile at the active site [9].
• The attempted Diels-Alder reaction between 9-phenylethynylfluorene and tetracyclone yields instead three products resulting from the dimerization of the isomeric allene [10].

Associations of Propadienylidene with other chemical compounds

• We report biosynthesis of the allene oxide (8R)-8,9-epoxyeicosa-(5Z,9,11Z,14Z)-tetraenoic acid via the (8R)-lipoxygenase metabolism of arachidonic acid in starfish oocytes [6].
• Characterization of the coral allene oxide synthase active site with UV-visible absorption, magnetic circular dichroism, and electron paramagnetic resonance spectroscopy: evidence for tyrosinate ligation to the ferric enzyme heme iron [11].
• Ab initio (MP2/6-311+G**) and density functional (B3LYP/6-311+G**) computations of 1:1 Br(2) complexes showed that the association energies of allene x Br(2) and ethene x Br(2) complexes are nearly the same but are greater than that of acetylene x Br(2) complexes [12].
• Incorporation of an allene unit into alpha-pinene: generation of the cyclic allene 2,7,7-trimethylbicyclo[4.1.1]octa-2,3-diene and its dimerization [13].
• Regio- and stereoselective palladium-catalyzed reactions of allene-substituted 1,3-dienes 1 in acetic acid at room temperature lead to cyclization with formation of a carbon-carbon bond between the middle carbon of the allene and the terminal carbon of the 1,3-diene [14].

Gene context of Propadienylidene

• We conclude that coral uses two parallel routes for the initial oxidation of polyenoic acids: the cyclooxygenase route, which leads to optically active prostaglandins, and the lipoxygenase/allene oxide synthase metabolism, the role of which remains to be established [5].
• We suggest that the same process initiates allene oxide synthesis, a conclusion that is also most compatible with the known chemistry of cytochromes P450 [15].
• In the cases of cyclohexa-1,2-diene (1), the isobenzene 2, and the isonaphthalene 7, the most stable structures having a planar allene moiety are the diradicals 1b, 2b, and 7b, representing the transition states for the racemization of 1a, 2a, and 7a and being less stable than the latter by 14.1, 8.9, and 11.2 kcal/mol, respectively [16].
• Transcript levels for the JA biosynthetic enzymes lipoxygenase, allene oxide synthase, and allene oxide cyclase were strongly increased during K(+) starvation and quickly decreased after K(+) resupply [17].
• The rise in jasmonates is accompanied by the expression of genes coding for an enzyme of JA biosynthesis (allene oxide synthase) and of a jasmonate-induced protein (JIP23) [18].

Analytical, diagnostic and therapeutic context of Propadienylidene

• Molecular cloning of an allene oxide synthase: a cytochrome P450 specialized for the metabolism of fatty acid hydroperoxides [19].

References