Department of Chemistry, University of Connecticut , Storrs, Connecticut 06269-3060, United States.
Department of Immunology and Medicine, University of Connecticut School of Medicine , Farmington, Connecticut 06030, United States.
Anal Chem. 2017 Mar 21;89(6):3583-3589. doi: 10.1021/acs.analchem.6b04901. Epub 2017 Feb 28.
Lipopeptides promote innate immune response and are related to disease pathology. To investigate the newly emerging roles of lipopeptides, accurate measurements of stereoisomers with multiple chiral centers are essential yet challenging. This work uses (3R)- and (3S)-(15-methyl-3-((13-methyltetradecanoyl)oxy)hexadecanoyl)glycyl-l-serine, abbreviated as l-serine-(R+S)-Lipid 654, to develop a method that combines chiral liquid chromatography, a diastereomeric mixture of isotopically labeled internal standards, and multiple reaction monitoring mass spectrometry. The new method allows for simultaneously determining the absolute configuration and quantity of stereoisomers of bacteria-derived lipopeptides. Total lipid extracts of nine evaluated bacteria strains had different amounts, but only the (R)-isoform of l-serine-Lipid 654. The developed method also allowed for the first quantitative analysis of hydrolysis of a nonphospholipid as a novel substrate of honey bee venom phospholipase A2.
脂肽可促进先天免疫反应，与疾病病理有关。为了研究脂肽新出现的作用，对具有多个手性中心的立体异构体进行准确测量至关重要，但也极具挑战性。本工作使用（3R）-和（3S）-（15-甲基-3-（（13-甲基十四烷酰基）氧基）十六烷酰基）甘氨酰-l-丝氨酸，缩写为 l-丝氨酸-（R+S）-脂肽 654，开发了一种结合手性液相色谱、同位素标记内标混合物和多反应监测质谱的方法。该新方法可同时确定细菌衍生脂肽的立体异构体的绝对构型和数量。对 9 种评估的细菌菌株的总脂质提取物进行了分析，发现它们的含量不同，但只有 l-丝氨酸-脂肽 654 的（R）异构体存在。该方法还首次定量分析了作为新型蜂毒磷脂酶 A2 水解物的非磷脂的水解。
