Direct qualitative analysis of triacylglycerols by electrospray mass spectrometry using a linear ion trap
Direct qualitative analysis of triacylglycerols by electrospray mass spectrometry using a linear ion trap
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DOI：
10.1016/j.jasms.2005.04.017
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发表时间：
2005-09-01
影响因子：
3.2
通讯作者：
Murphy, RC
中科院分区：
文献类型：
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作者：
McAnoy, AM;Wu, CC;Murphy, RC
从生物样品中分离出的三酰基甘油(TAG)给质谱分析带来了挑战，因为自然存在的TAG具有复杂性，可能包含不同的脂肪酰基取代基，导致大量分子物种具有相同的元素组成。我们使用线性离子陷阱质谱仪研究了使用质谱学来获得关于存在于三酰甘油复杂混合物中的单个TAG分子物种的明确信息。TAG的氨加合物[M+NH4](+)是通过电喷雾电离产生的，这使得可以测定每个TAG分子物种的分子量。通过氚标记、MS/MS和MS3实验研究了[M+NH4](+)和后续碎片离子的分解机理。碰撞诱导的[M+NH4](+)离子的分解导致NH3和酰基侧链(作为羧酸)的中性损失而生成二酰基产物离子。MS/MS数据被用来确定给定的[M+NH4](+)离子存在的每个酰基，并且该信息可以与分子量数据相结合来识别存在于生物提取物中的可能的标记分子种类。随后，MS3对生成的二酰基产物离子进行了实验，这些离子产生了丙烯酸根(RCO)和相关离子，从而实现了明确的TAG分子指定。MS、MS/MS和MS3实验的这些策略被应用于鉴定从RAW 264.7细胞中提取的中性脂的复杂混合物中的成分。
Triacylglycerols (TAGs) isolated from a biological sample provide a challenge for mass spectrometric analysis because of the complexity of naturally occurring TAGs, which may contain different fatty acyl substituents resulting in a large number of molecular species having the identical elemental composition. We have investigated the use of mass spectrometry to obtain unambiguous information as to the individual TAG molecular species present in a complex mixture of triacylglycerols using a linear ion trap mass spectrometer. Ammonium adducts of TAGS, [M + NH4](+), were generated by electrospray ionization, which permitted the molecular weight of each TAG molecular species to be determined. The mechanisms involved in the decomposition of the [M + NH4](+) and subsequent fragment ions were investigated using deuterium labeling, MS/MS, and MS3 experiments. Collision induced decomposition of [M + NH4](+) ions resulted in the neutral loss of NH3 and an acyl side-chain (as a carboxylic acid) to generate a diacyl product ion. MS/MS data were used to identify each acyl group present for a given [M + NH4](+) ion, and this information could be combined with molecular weight data to identify possible TAG molecular species present in a biological extract. Subsequent MS3 experiments on the resultant diacyl product ions, which gave rise to acylium (RCO) and related ions, enabled unambiguous TAG molecular assignments. These strategies of MS, MS/MS, and MS3 experiments were applied to identify components within a complex mixture of neutral lipids extracted from RAW 264.7 cells.