羥脂是從脂肪酸產(chǎn)生的具有生物活性的脂類(lèi),。在植物中，羥脂通道產(chǎn)生前列腺素一樣的,、被稱(chēng)為茉莉酮酸的植物激素,，同時(shí)產(chǎn)生能抵抗壓力和使水果及蔬菜具有其特有香味的綠葉揮發(fā)物,。
現(xiàn)在，羥脂通道酶“丙二烯氧化合酶”（AOS）（呈自由狀態(tài),，與基質(zhì)相結(jié)合）的晶體結(jié)構(gòu)已被確定,。該結(jié)構(gòu)顯示了這種酶是怎樣控制關(guān)鍵中間體的活性的，并且說(shuō)明,，AOS活性點(diǎn)（與茉莉酮酸的合成有關(guān)）上關(guān)鍵氨基酸的突變可將其轉(zhuǎn)變成一種過(guò)氧化物裂解酶（合成綠葉揮發(fā)物的酶）,。另外，比較研究表明,，羥脂生物合成基因存在于植物和動(dòng)物的最后共同祖先中,，但在演化過(guò)程中在除少數(shù)幾個(gè)后生動(dòng)物分支以外的所有動(dòng)物身上都丟失了。（生物谷Bioon.com）
生物谷推薦原始出處：
Nature 455, 363-368 (18 September 2008) | doi:10.1038/nature07307
Structural insights into the evolutionary paths of oxylipin biosynthetic enzymes
Dong-Sun Lee, Pierre Nioche, Mats Hamberg & C. S. Raman
The oxylipin pathway generates not only prostaglandin-like jasmonates but also green leaf volatiles (GLVs), which confer characteristic aromas to fruits and vegetables. Although allene oxide synthase (AOS) and hydroperoxide lyase are atypical cytochrome P450 family members involved in the synthesis of jasmonates and GLVs, respectively, it is unknown how these enzymes rearrange their hydroperoxide substrates into different products. Here we present the crystal structures of Arabidopsis thaliana AOS, free and in complex with substrate or intermediate analogues. The structures reveal an unusual active site poised to control the reactivity of an epoxyallylic radical and its cation by means of interactions with an aromatic -system. Replacing the amino acid involved in these steps by a non-polar residue markedly reduces AOS activity and, unexpectedly, is both necessary and sufficient for converting AOS into a GLV biosynthetic enzyme. Furthermore, by combining our structural data with bioinformatic and biochemical analyses, we have discovered previously unknown hydroperoxide lyase in plant growth-promoting rhizobacteria, AOS in coral, and epoxyalcohol synthase in amphioxus. These results indicate that oxylipin biosynthetic genes were present in the last common ancestor of plants and animals, but were subsequently lost in all metazoan lineages except Placozoa, Cnidaria and Cephalochordata.
