Institute of Organic Chemistry, Technical University of Braunschweig, Hagenring 30, 38106 Braunschweig, Germany.
Chembiochem. 2010 Feb 15;11(3):417-25. doi: 10.1002/cbic.200900668.
The volatiles released by Phaeobacter gallaeciensis, Oceanibulbus indolifex and Dinoroseobacter shibae have been investigated by GC-MS, and several MeSH-derived sulfur volatiles have been identified. An important sulfur source in the oceans is the algal metabolite dimethylsulfoniopropionate (DMSP). Labelled [2H6]DMSP was fed to the bacteria to investigate the production of volatiles from this compound through the lysis pathway to [2H6]dimethylsulfide or the demethylation pathway to [2H3]-3-(methylmercapto)propionic acid and lysis to [2H3]MeSH. [2H6]DMSP was efficiently converted to [2H3]MeSH by all three species. Several DMSP derivatives were synthesised and used in feeding experiments. Strong dealkylation activity was observed for the methylated ethyl methyl sulfoniopropionate and dimethylseleniopropionate, as indicated by the formation of EtSH- and MeSeH-derived volatiles, whereas no volatiles were formed from dimethyltelluriopropionate. In contrast, the dealkylation activity for diethylsulfoniopropionate was strongly reduced, resulting in only small amounts of EtSH-derived volatiles accompanied by diethyl sulfide in P. gallaeciensis and O. indolifex, while D. shibae produced the related oxidation product diethyl sulfone. The formation of diethyl sulfide and diethyl sulfone requires the lysis pathway, which is not active for [2H6]DMSP. These observations can be explained by a shifted distribution between the two competing pathways due to a blocked dealkylation of ethylated substrates.
海洋发光杆菌、海洋吲哚黄杆菌和海弧菌所释放的挥发性物质已通过 GC-MS 进行了研究,并鉴定出了几种基于 MeSH 的硫挥发性物质。海洋中一个重要的硫源是藻类代谢物二甲硫基丙酸盐(DMSP)。将标记的 [2H6]DMSP 喂食给细菌,以研究通过裂解途径从该化合物产生挥发性物质[2H6]二甲硫醚或通过脱甲基途径产生 [2H3]-3-(甲硫基)丙酸和裂解为 [2H3]MeSH。所有三种细菌都能有效地将 [2H6]DMSP 转化为 [2H3]MeSH。几种 DMSP 衍生物被合成并用于喂养实验。甲基化的乙基甲基磺丙酸盐和二甲基硒丙酸盐表现出强烈的脱烷基活性,如形成 EtSH 和 MeSeH 衍生的挥发性物质所表明的那样,而二甲基碲丙酸盐则没有形成挥发性物质。相比之下,二乙基磺丙酸盐的脱烷基活性大大降低,导致仅产生少量的 EtSH 衍生的挥发性物质,并伴有 P. gallaeciensis 和 O. indolifex 中的二乙基硫醚,而 D. shibae 则产生相关的氧化产物二乙基砜。二乙基硫醚和二乙基砜的形成需要裂解途径,而该途径对 [2H6]DMSP 不活跃。这些观察结果可以通过由于乙烷基化底物的脱烷基受阻而导致两种竞争途径之间分布的变化来解释。