Allene oxide synthase

Figure 8.6 A diagram of the oxylipin pathway. LOX lipoxygenase AOS allene oxide synthase HPL hydroperoxide lyase AOC allene oxide cyclase OPDA Reductase 12-oxo-phytodienoic acid-10,11-reductase.

LAU, S.M., HARDER, P.A., O KEEFE, D.P., Low carbon monoxide affinity allene oxide synthase is the predominant cytochrome P450 in many plant tissues, Biochemistry, 1993,32,1945-1950. 

SONG, W.C., FUNK, C.D., BRASH, A.R., Molecular cloning of an allene oxide synthase A cytochrome P450 specialized for the metabolism of fatty acid hydroperoxides, Proc. Natl. Acad. Sci. USA, 1993, 90, 8519-8523. 

LAUDERT, D., PFANNSCHMIDT, U., LOTTSPEICH, F HOLLANDER-CZYTKO, H., WEILER, E.W., Cloning, molecular and functional characterization of Arabidopsis thaliana allene oxide synthase (CYP74) the first enzyme for the octadecanoid pathway to jasmonates, Plant Mol. Biol., 1996,31,323-335. 

This enzyme [EC 5.3.99.6] catalyzes the conversion of (9Z)-(135 )-12,13-epoxyoctadeca-9,ll,15-trienoate to (15Z)-12-oxophyto-10,15-dienoate. The allene oxides which are formed by the action of allene-oxide synthase [EC 4.2.1.92] are converted into cyclopentenone derivatives. 

ALLANTOICASE ALLANTOINASE ALLENE OXIDE CYCLASE ALLENE OXIDE SYNTHASE ALU IN LYASE... 

In plants the 13-hydroperoxide produced from linolenic acid by lipoxygenase (Sect. 23.4.1.2) can be converted to the allene oxide by allene oxide synthase followed by cyclisation, reduction and -oxidation to form jasmonic acid, an important plant growth factor the corresponding methyl jasmonate is a valuable flavour and fragrance compound that imparts a sweet-floral, jasmine-like note... 

FROELICH, J.E., ITOH, A., HOWE, G.A., Tomato allene oxide synthase and fatty acid hydroperoxide lyase, two cytochrome P450s involved in oxylipin metabolism, are targeted to different membranes of chloroplast envelope., Plant Physiol., 2001,125,306-317. 

ZIEGLER, J., KEINANEN, M., BALDWIN, I.T., Herbivore-induced allene oxide synthase transcripts and jasmonic acid in Nicotiana attenuata Phytochemistry, 2001,58,729-738. 

JAs are derived from linolenic acid via an octadecanoid pathway consisting of several enzymatic steps (Figure 36). Multiple compartments in plant cells participate in JA synthesis. The early steps of this pathway occur in chloroplasts, where linolenic acid is converted to OPDA by means of the three enzymes lipoxygenase (LOX), allene oxide synthase (AOS), and allene oxide cyclase (AOC).867-869 Linolenic acid is oxygenated by 13-LOX producing a peroxidized fatty acid 13-hydroperoxylinolenic acid. The product is subsequently metabolized by AOS to an unstable compound allene oxide. Allene oxide is sequentially converted by AOC to produce OPDA. An alternative pathway from another trienoic fatty acid, hexadecatrienoic acid (16 3), is present in chloroplasts.870 In this pathway, dinor OPDA is produced instead of OPDA. OPDA and dinor OPDA are transported into the peroxisome. An ABC transporter involved in this transport was identified in... 

C. Wastemack (2000). Allene oxide synthases of barley (Hordeum vulgare cv. Salome) Tissues specific regulation in seedling development. Plant J. 21, 199-213. 

Howe, G.A., G.I. Lee, A. Itoh, L. Li, and A.E. DeRocher (2000). Cytochrome P450-depend-ent metabolism of oxylipids in tomato. Cloning and expression of allene oxide synthase and fatty acid hydroperoxide lyase. Plant Physiol. 123, 711-724. 

Li L, Chang Z, Pan Z, Fu ZQ, Wang X (2008) Modes of heme binding and substrate access for cytochrome P450 CYP74A revealed by crystal structures of allene oxide synthase. Proc Natl Acad Sci U S A 105 13883-13888... 

Brash AR (2009) Mechanistic aspects of CYP74 allene oxide synthases and related cytochrome P450 enzymes. Phytochemistry 70 1522-1531... 

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