Preferential inhibition of the lycopene epsilon-cyclase by the substituted triethylamine compound MPTA in higher plants.
Preferential inhibition of the lycopene epsilon-cyclase by the substituted triethylamine compound MPTA in higher plants.
复制标题
DOI：
--
复制
发表时间：
2006
影响因子：
4.3
通讯作者：
Denise Phillip;A. Young
中科院分区：
文献类型：
--
作者：
Denise Phillip;A. Young
除了植物叶片组织中常见的类胡萝卜素外，生菜（ Lactuca sativa）不同寻常地含有大量的二醇乳黄质。这种类胡萝卜素具有两个ε -末端基团，它的存在为研究取代的三乙胺化合物2 -（4 -甲基苯氧基）三乙胺（MPTA）在类胡萝卜素生物合成过程中对β -和ε -末端基团环化的影响提供了一个良好的模型。用10或20微摩尔MPTA处理显著降低了β -胡萝卜素和新黄质的水平（高达18倍），而紫黄质和叶黄素的水平受影响较小（降低4倍）。相比之下，即使在最高抑制剂浓度下，乳黄质的水平也没有降低，并且在10微摩尔MPTA时，这种叶黄素的水平增加了一倍。从处理过的植物中分离出的大量捕光复合物（LHCIIb）的色素化学计量表明，乳黄质成功地在两个叶黄素结合位点，即L2和N1，替代了叶黄素和新黄质。环化的抑制伴随着番茄红素以及痕量的δ -胡萝卜素和这些前体的一些含氧衍生物的积累。鉴定出了两种形式的单羟基番茄红素以及单环氧δ -胡萝卜素。
In addition to the usual complement of carotenoids found in the plant leaf tissues, lettuce (Lactuca sativa), unusually, possesses large amounts of the diol lactucaxanthin. This carotenoid possesses two epsilon-end-groups and its presence provides a good model in which to study the effects of the substituted triethylamine compound 2-(4-methylphenoxy)triethylamine (MPTA) on the cyclisation of beta- and epsilon-end-groups during the biosynthesis of carotenoids. Treatment with 10 or 20microM MPTA significantly reduced levels of both beta-carotene and neoxanthin (up to 18-fold), whilst levels of violaxanthin and lutein were less affected (4-fold reduction). In contrast, levels of lactucaxanthin were not reduced even at the highest inhibitor concentration, and at 10microM MPTA levels of this xanthophyll doubled. The pigment stoichiometry of the bulk light-harvesting complex (LHCIIb) isolated from treated plants shows that lactucaxanthin successfully substituted for lutein and neoxanthin in two of the xanthophyll binding sites, namely L2 and N1. Inhibition of cyclisation was accompanied by the accumulation of lycopene and trace amounts of delta-carotene and a number of oxygenated derivatives of these precursors. Two forms of mono-hydroxy lycopene were identified together with mono-epoxy delta-carotene.