Institute of Molecular Physiology and Biotechnology of Plants, University of Bonn, 53115 Bonn, Germany.
J Lipid Res. 2011 May;52(5):1039-54. doi: 10.1194/jlr.D013987. Epub 2011 Mar 7.
Glycerolipids, sphingolipids, and sterol lipids constitute the major lipid classes in plants. Sterol lipids are composed of free and conjugated sterols, i.e., sterol esters, sterol glycosides, and acylated sterol glycosides. Sterol lipids play crucial roles during adaption to abiotic stresses and plant-pathogen interactions. Presently, no comprehensive method for sterol lipid quantification in plants is available. We used nanospray ionization quadrupole-time-of-flight mass spectrometry (Q-TOF MS) to resolve and identify the molecular species of all four sterol lipid classes from Arabidopsis thaliana. Free sterols were derivatized with chlorobetainyl chloride. Sterol esters, sterol glycosides, and acylated sterol glycosides were ionized as ammonium adducts. Quantification of molecular species was achieved in the positive mode after fragmentation in the presence of internal standards. The amounts of sterol lipids quantified by Q-TOF MS/MS were validated by comparison with results obtained with TLC/GC. Quantification of sterol lipids from leaves and roots of phosphate-deprived A. thaliana plants revealed changes in the amounts and molecular species composition. The Q-TOF method is far more sensitive than GC or HPLC. Therefore, Q-TOF MS/MS provides a comprehensive strategy for sterol lipid quantification that can be adapted to other tandem mass spectrometers.
甘油磷脂、鞘脂和甾醇脂构成了植物中的主要脂质类群。甾醇脂由游离甾醇和结合甾醇组成，即甾醇酯、甾醇糖苷和酰化甾醇糖苷。甾醇脂在植物适应非生物胁迫和植物-病原菌相互作用中起着至关重要的作用。目前，植物中甾醇脂定量的综合方法尚未建立。我们使用纳喷雾电离四极杆飞行时间质谱（Q-TOF MS）解析并鉴定了拟南芥中所有四种甾醇脂类的分子种类。游离甾醇用氯贝特酰氯衍生化。甾醇酯、甾醇糖苷和酰化甾醇糖苷作为铵加合物进行离子化。在存在内标物的情况下，通过碎裂，在正模式下实现了分子种类的定量。用 Q-TOF MS/MS 定量的甾醇脂的量通过与 TLC/GC 获得的结果进行比较来验证。对缺磷拟南芥叶片和根系中甾醇脂的定量表明，甾醇脂的含量和分子种类组成发生了变化。Q-TOF 法比 GC 或 HPLC 灵敏得多。因此，Q-TOF MS/MS 为甾醇脂定量提供了一种综合策略，可适用于其他串联质谱仪。
