Cui Yiling, Frey Rebecca L, Ferry John L, Ferguson P Lee
Department of Chemistry and Biochemistry, University of South Carolina, Columbia, SC 29208, USA.
Rapid Commun Mass Spectrom. 2009 Apr;23(8):1212-20. doi: 10.1002/rcm.3991.
A reversed-phase high-performance liquid chromatography/electrospray tandem mass spectrometry method was developed for the characterization of hydroxyl radical oxidation products of N-hexanoyl-homoserine lactone (C6-HSL), a member of the N-acylhomoserine lactone (AHL) class of microbial quorum-sensing signaling molecules identified in many Gram-negative strains of bacteria. Six products were identified: four with molecular weight (MW) of 213 and two with MW of 260. The characteristic product ions formed through collision-induced dissociation (CID) provided diagnostic structural information. One of the photolysis products was determined to be N-(3-oxohexanoyl)homoserine lactone (3OC6-HSL), a highly active quorum-sensing signal, by comparison with a reference standard. Three structural isomers with the same mass as 3OC6-HSL were identified as acyl side chain oxidized C6-HSL (keto/enol functionalized) by accurate mass measurement and the structures of these products were proposed from CID spectral interpretation. Two structural isomers formed from concurrent oxidation and nitration of C6-HSL were also observed and their structures were postulated based on CID spectra. In addition to the six hydroxyl radical oxidation products formed from the C6-HSL precursor, five additional compounds generated from combined oxidation and lactonolysis of C6-HSL were identified and structures were postulated.
建立了一种反相高效液相色谱/电喷雾串联质谱法，用于表征N-己酰基高丝氨酸内酯（C6-HSL）的羟基自由基氧化产物。C6-HSL是在许多革兰氏阴性菌中发现的N-酰基高丝氨酸内酯（AHL）类微生物群体感应信号分子的一员。鉴定出六种产物：四种分子量（MW）为213，两种分子量为260。通过碰撞诱导解离（CID）形成的特征产物离子提供了诊断性结构信息。通过与参考标准品比较，确定其中一种光解产物为N-（3-氧代己酰基）高丝氨酸内酯（3OC6-HSL），一种高活性群体感应信号。通过精确质量测量，鉴定出三种与3OC6-HSL质量相同的结构异构体为酰基侧链氧化的C6-HSL（酮/烯醇官能化），并根据CID光谱解释提出了这些产物的结构。还观察到由C6-HSL同时氧化和硝化形成的两种结构异构体，并根据CID光谱推测了它们的结构。除了由C6-HSL前体形成的六种羟基自由基氧化产物外，还鉴定出由C6-HSL的联合氧化和内酯分解产生的另外五种化合物，并推测了其结构。
