Jung Verena, Thibaut Thierry, Meinesz Alexandre, Pohnert Georg
Max-Planck-Institut für Chemische Okologie, Jena, Germany.
J Chem Ecol. 2002 Oct;28(10):2091-105. doi: 10.1023/a:1020710230532.
The invasive green alga, Caulerpa taxifolia, that has spread rapidly after its introduction into the Mediterranean and the North American Pacific, reacts to wounding by transforming its major metabolite caulerpenyne. This wound-activated reaction involves the transformation of the bis-enol acetate moiety of 1, releasing reactive 1,4-dialdehydes. The ability to perform this transformation is found also in both the noninvasive Mediterranean C. prolifera and the invasive C. racemosa. Trapping experiments, as well as transformation of the model substrate geranyl acetate, suggest that all three investigated Caulerpa spp. rely on esterases that act upon wounding of the algae by subsequently removing the three acetate residues of caulerpenyne. The resulting reactive 1,4-dialdehyde oxytoxin 2 can be identified by liquid chromatography-mass spectrometry and is unstable in the wounded tissue. Caulerpenyne transformation occurs rapidly, and severe tissue damage caused degradation of more than 50% of the stored caulerpenyne within 1 min in all three algae. Prevention of the enzymatic reaction before extraction, by shock freezing the tissue with liquid nitrogen, was used for the determination of the caulerpenyne content in intact algae. It gives about twofold higher values compared to an established methanol extraction protocol. The speed and mechanism of the wound-activated transformation, as well as the caulerpenyne content in intact tissue of invasive and noninvasive Caulerpa spp., are comparable. Thus, this enzymatic transformation, despite being fast and efficient, is likely not the key for the success of the investigated invasive species.
入侵性绿藻杉叶蕨藻，在被引入地中海和北美太平洋后迅速扩散，它通过转化其主要代谢产物二倍半萜来应对创伤。这种创伤激活反应涉及到1的双烯醇醋酸酯部分的转化，释放出具有反应活性的1,4 -二醛。在非入侵性的地中海粗枝藻和入侵性的总状蕨藻中也发现了进行这种转化的能力。捕获实验以及模型底物醋酸香叶酯的转化表明，所有三种被研究的蕨藻属物种都依赖酯酶，这些酯酶在藻类受到创伤时发挥作用，随后去除二倍半萜的三个醋酸残基。通过液相色谱 - 质谱联用可以鉴定出由此产生的具有反应活性的1,4 -二醛氧化毒素2，并且它在受伤组织中不稳定。二倍半萜的转化迅速发生，在所有三种藻类中，严重的组织损伤在1分钟内导致超过50%储存的二倍半萜降解。在提取前通过用液氮速冻组织来防止酶促反应，用于测定完整藻类中二倍半萜的含量。与既定的甲醇提取方案相比，它给出的值高出约两倍。入侵性和非入侵性蕨藻属物种在完整组织中的创伤激活转化速度和机制以及二倍半萜含量相当。因此，这种酶促转化尽管快速且高效，但可能不是所研究的入侵物种成功的关键。
