Identification of the structure and origin of a thioacidolysis marker compound for ferulic acid incorporation into angiosperm lignins (and an indicator for cinnamoyl CoA reductase deficiency)
Identification of the structure and origin of a thioacidolysis marker compound for ferulic acid incorporation into angiosperm lignins (and an indicator for cinnamoyl CoA reductase deficiency)
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DOI：
10.1111/j.1365-313x.2007.03345.x
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发表时间：
2008-01-01
期刊：
影响因子：
7.2
通讯作者：
Lapierre, Catherine
中科院分区：
文献类型：
--
作者：
Ralph, John;Kim, Hoon;Lapierre, Catherine
通过硫代酸解降解方法从木质素衍生的分子标记化合物，其用于当阿魏酸掺入被子植物（白杨、拟南芥、烟草）中的木质素中时产生的结构，已在结构上鉴定为1，2，2-三硫乙基乙基愈创木酚[1-（4-羟基-3-甲氧基苯基）-1，2，2-三（乙硫基）乙烷]。其截短的侧链和独特的氧化态表明，它来自阿魏酸，在木质化过程中经历了双-8-O-4（交叉）耦合，通过模型研究验证。这种结构的诊断轮廓被发现在二维C-13-H-1相关（HSQC）NMR光谱的木质素分离肉桂酰CoA还原酶（CCR）缺陷白杨。由于在木质化过程中可能存在阿魏酸的正常（即非转基因）植物，特别是禾本科植物中也释放出低水平的标记物，因此该标记物通常仅是CCR缺乏的指示物，但在木本被子植物如白杨中是可靠的标记物。其衍生物，连同4-O-醚化阿魏酸的证据，强烈暗示阿魏酸被纳入被子植物木质素。它的末端自由基偶联反应表明，阿魏酸应被认为是一个真正的木质素前体。此外，阿魏酸的掺入提供了在聚合物中产生分支点的新机制。这一发现与最近一项关于CCR缺陷型拟南芥的研究报告截然不同。
A molecular marker compound, derived from lignin by the thioacidolysis degradative method, for structures produced when ferulic acid is incorporated into lignin in angiosperms (poplar, Arabidopsis, tobacco), has been structurally identified as 1,2,2-trithioethyl ethylguaiacol [1-(4-hydroxy-3-methoxyphenyl)-1,2,2-tris(ethylthio)ethane]. Its truncated side chain and distinctive oxidation state suggest that it derives from ferulic acid that has undergone bis-8-O-4 (cross) coupling during lignification, as validated by model studies. A diagnostic contour for such structures is found in two-dimensional C-13-H-1 correlated (HSQC) NMR spectra of lignins isolated from cinnamoyl CoA reductase (CCR)-deficient poplar. As low levels of the marker are also released from normal (i.e. non-transgenic) plants in which ferulic acid may be present during lignification, notably in grasses, the marker is only an indicator for CCR deficiency in general, but is a reliable marker in woody angiosperms such as poplar. Its derivation, together with evidence for 4-O-etherified ferulic acid, strongly implies that ferulic acid is incorporated into angiosperm lignins. Its endwise radical coupling reactions suggest that ferulic acid should be considered an authentic lignin precursor. Moreover, ferulic acid incorporation provides a new mechanism for producing branch points in the polymer. The findings sharply contradict those reported in a recent study on CCR-deficient Arabidopsis.