Physcomitrella patens has lipoxygenases for both eicosanoid and octadecanoid pathways
Physcomitrella patens has lipoxygenases for both eicosanoid and octadecanoid pathways
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DOI：
10.1016/j.phytochem.2008.11.012
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发表时间：
2009-01-01
期刊：
影响因子：
3.8
通讯作者：
Grimes, Howard
中科院分区：
文献类型：
--
作者：
Anterola, Aldwin;Goebel, Cornelia;Grimes, Howard
除了较短链C18 α-亚麻酸和亚油酸之外，苔藓还具有大量的长链C20多不饱和脂肪酸，如花生四烯酸和二十碳五烯酸，它们是开花植物中脂氧合酶的典型底物。为了确定苔藓脂肪氧合酶所使用的脂肪酸底物，将八个小立碗藓脂肪氧合酶基因在大肠杆菌中异源表达，然后使用亚油酸、α-亚麻酸和花生四烯酸作为底物分析脂肪氧合酶活性。在这8种藓类脂肪氧合酶中，只有7种在体外具有酶活性，其中2种选择性地以花生四烯酸为底物，而另外5种优选α-亚麻酸。基于使用克拉克型氧电极的酶测定，所有的活性脂氧合酶的最适pH为7.0，除了一个在pH 5.0具有最高活性。HPLC分析表明，两种花生四烯酸脂氧合酶的主要产物为（12 S）-过氧化二十碳四烯酸，而其他5种脂氧合酶主要由α-亚麻酸生成（13 S）-过氧化十八碳三烯酸。这些结果表明，藓类植物可能有C20和C18为基础的氧化脂途径。爱思唯尔有限公司出版
Mosses have substantial amounts of long chain C20 polyunsaturated fatty acids, such as arachidonic and eicosapentaenoic acid, in addition to the shorter chain C18 alpha-linolenic and linoleic acids, which are typical substrates of lipoxygenases in flowering plants. To identify the fatty acid substrates used by moss lipoxygenases, eight lipoxygenase genes from Physcomitrella patens were heterologously expressed in Escherichia coli, and then analyzed for lipoxygenase activity using linoleic, alpha-linolenic and arachidonic acids as substrates. Among the eight moss lipoxygenases, only seven were found to be enzymatically active in vitro, two of which selectively used arachidonic acid as the substrate, while the other five preferred alpha-linolenic acid. Based on enzyme assays using a Clark-type oxygen electrode, all of the active lipoxygenases had an optimum pH at 7.0, except for one with highest activity at pH 5.0. HPLC analyses indicated that the two arachidonic acid lipoxygenases form (12S)-hydroperoxy eicosatetraenoic acid as the main product, while the other five lipoxygenases produce mainly (13S)-hydroperoxy octadecatrienoic acid from alpha-linolenic acid. These results suggest that mosses may have both C20 and C18 based oxylipin pathways. Published by Elsevier Ltd.